From patchwork Fri Aug 19 22:17:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949299 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 750F6C32772 for ; Fri, 19 Aug 2022 22:19:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240276AbiHSWTR (ORCPT ); Fri, 19 Aug 2022 18:19:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240485AbiHSWTI (ORCPT ); Fri, 19 Aug 2022 18:19:08 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF2E3D8B37; Fri, 19 Aug 2022 15:19:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=efMK60nr83yuRCx5Ljwx52Fk9k5SHvdIGer1v3Qxdhs=; b=SjQSOrdIC0PRcYZolS77irogck Mcx5v/0ZNaHxyEbxFL3onPgr5fMu09Pd2ybtyiuoazQiRcE4q1BCAdwvuZlYFgooxjD3BxoZoH4PK E/IlV6B+dBp+jSqRHfRRW0pIXAMZz1tIYerq39GhYuucnq6cSpZZ0C96yp+R/lJeJCEuPn+qomTxx BGxXGbnwkISEpDio7Vmfl6/6+0bvNYjEYtE6gc8UcjowEqH3UBtnvIUbDmL7qJyOrM5MVw4W2US5T 3K1YJX1V/eWgE3S5pK2h+HxIYqHNfmis/7gh2PMnSysILIOzmrBUaMLqgXhAwCFkg2rzBmE/TgWP6 uuEMeQ0Q==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAKN-00Casf-VT; Sat, 20 Aug 2022 00:18:59 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , linux-arm-kernel@lists.infradead.org, Marc Zyngier , Russell King Subject: [PATCH V3 01/11] ARM: Disable FIQs (but not IRQs) on CPUs shutdown paths Date: Fri, 19 Aug 2022 19:17:21 -0300 Message-Id: <20220819221731.480795-2-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently the regular CPU shutdown path for ARM disables IRQs/FIQs in the secondary CPUs - smp_send_stop() calls ipi_cpu_stop(), which is responsible for that. IRQs are architecturally masked when we take an interrupt, but FIQs are high priority than IRQs, hence they aren't masked. With that said, it makes sense to disable FIQs here, but there's no need for (re-)disabling IRQs. More than that: there is an alternative path for disabling CPUs, in the form of function crash_smp_send_stop(), which is used for kexec/panic path. This function relies on a SMP call that also triggers a busy-wait loop [at machine_crash_nonpanic_core()], but without disabling FIQs. This might lead to odd scenarios, like early interrupts in the boot of kexec'd kernel or even interrupts in secondary "disabled" CPUs while the main one still works in the panic path and assumes all secondary CPUs are (really!) off. So, let's disable FIQs in both paths and *not* disable IRQs a second time, since they are already masked in both paths by the architecture. This way, we keep both CPU quiesce paths consistent and safe. Cc: Marc Zyngier Cc: Michael Kelley Cc: Russell King Signed-off-by: Guilherme G. Piccoli --- V3: - No changes. V2: - Small wording improvement (thanks Michael Kelley); - Only disable FIQs, since IRQs are masked by architecture definition when we take an interrupt. Thanks a lot Russell and Marc for the discussion [0]. Should we add a Fixes tag here? If so, maybe the proper target is: b23065313297 ("ARM: 6522/1: kexec: Add call to non-crashing cores through IPI") [0] https://lore.kernel.org/lkml/Ymxcaqy6DwhoQrZT@shell.armlinux.org.uk/ arch/arm/kernel/machine_kexec.c | 2 ++ arch/arm/kernel/smp.c | 5 ++--- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index f567032a09c0..0b482bcb97f7 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -77,6 +77,8 @@ void machine_crash_nonpanic_core(void *unused) { struct pt_regs regs; + local_fiq_disable(); + crash_setup_regs(®s, get_irq_regs()); printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has crashed\n", smp_processor_id()); diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 978db2d96b44..36e6efad89f3 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -600,6 +600,8 @@ static DEFINE_RAW_SPINLOCK(stop_lock); */ static void ipi_cpu_stop(unsigned int cpu) { + local_fiq_disable(); + if (system_state <= SYSTEM_RUNNING) { raw_spin_lock(&stop_lock); pr_crit("CPU%u: stopping\n", cpu); @@ -609,9 +611,6 @@ static void ipi_cpu_stop(unsigned int cpu) set_cpu_online(cpu, false); - local_fiq_disable(); - local_irq_disable(); - while (1) { cpu_relax(); wfe(); From patchwork Fri Aug 19 22:17:22 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949300 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E18FDC32773 for ; Fri, 19 Aug 2022 22:20:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240913AbiHSWUK (ORCPT ); Fri, 19 Aug 2022 18:20:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240351AbiHSWTy (ORCPT ); Fri, 19 Aug 2022 18:19:54 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ED0A311231B; Fri, 19 Aug 2022 15:19:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=6/bnVK8C59Zdi0xRlMVaj0E9n3r0rDyiTtpOzSklScI=; b=YDFmAyxwqCNKkk/EO7h/cdG+Vb Bikhb+/65tLMaFYHZ5lUs066mD5fF2Jc5SsJXm9Jcw9L4T3OGqDryMv1WCbGTOtyOu5pHtabgOk3m WDNVbwsKhzb9co3ZkSrqKNoE4GMHNELEJ72Y2Xdlp548ephFdzxA2eaG+EfEiBboPp1hwXjOfhnIm Ahl/KUo4ULnE5OgnP6kDLFk3nbldsaQAj+5d4NvKCbr6MATTMnWNw1GJm3TS53LpgSUvtvhIESW6m MzVfyEK5JdHfZV43mQ+egvPqzyvlWsdJJRO0OGCY3bnthoW6eLVHJl82GiTM8iJPd5eeSV3riIZR/ 3PUd/dvA==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAL4-00Cau4-La; Sat, 20 Aug 2022 00:19:40 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , Arjan van de Ven , Cong Wang , Sebastian Andrzej Siewior , Valentin Schneider , Xiaoming Ni Subject: [PATCH V3 02/11] notifier: Add panic notifiers info and purge trailing whitespaces Date: Fri, 19 Aug 2022 19:17:22 -0300 Message-Id: <20220819221731.480795-3-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Although many notifiers are mentioned in the comments, the panic notifiers infrastructure is not. Also, the file contains some trailing whitespaces. Fix both issues here. Cc: Arjan van de Ven Cc: Cong Wang Cc: Sebastian Andrzej Siewior Cc: Valentin Schneider Cc: Xiaoming Ni Reviewed-by: Baoquan He Signed-off-by: Guilherme G. Piccoli --- V3: - Added Baoquan review tag - thanks! V2: - No changes. include/linux/notifier.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/include/linux/notifier.h b/include/linux/notifier.h index aef88c2d1173..d5b01f2e3fcc 100644 --- a/include/linux/notifier.h +++ b/include/linux/notifier.h @@ -208,12 +208,12 @@ static inline int notifier_to_errno(int ret) /* * Declared notifiers so far. I can imagine quite a few more chains - * over time (eg laptop power reset chains, reboot chain (to clean + * over time (eg laptop power reset chains, reboot chain (to clean * device units up), device [un]mount chain, module load/unload chain, - * low memory chain, screenblank chain (for plug in modular screenblankers) + * low memory chain, screenblank chain (for plug in modular screenblankers) * VC switch chains (for loadable kernel svgalib VC switch helpers) etc... */ - + /* CPU notfiers are defined in include/linux/cpu.h. */ /* netdevice notifiers are defined in include/linux/netdevice.h */ @@ -224,6 +224,8 @@ static inline int notifier_to_errno(int ret) /* Virtual Terminal events are defined in include/linux/vt.h. */ +/* Panic notifiers are defined in include/linux/panic_notifier.h. */ + #define NETLINK_URELEASE 0x0001 /* Unicast netlink socket released */ /* Console keyboard events. From patchwork Fri Aug 19 22:17:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949301 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49191C32773 for ; Fri, 19 Aug 2022 22:21:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241247AbiHSWVP (ORCPT ); Fri, 19 Aug 2022 18:21:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241023AbiHSWVN (ORCPT ); Fri, 19 Aug 2022 18:21:13 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BDE99108975; Fri, 19 Aug 2022 15:21:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=w+V+d2Ou90II75S8tjeZPRXSUk1hOHxUHRxe/lCKYf8=; b=GcJDyWLUFBDhdhZRicD7s2hGOp JNq9aL5jXzUOnIeWtwVFCPgVcltgOhopGclsa1YufcOPLbtTcP52b96sRcg4Rr5NnLWUnqDdbBLRf NB6idHbm9fRY0m1Lf4ADFrv9tOw+wBEwSzawjHvCBKjAeiOSlrtuZFD2tfR6s3JAfm+lJDZx5WGTE B2t21P0zsAbg8Snpm8jCtem3l7gcR/0NlgfLESKnD/RfPAXhKLHmOYrtiI7YWJkYYWt0U30EqV8yO v9sbxOm+eq6ThJinbMItFxXhaYH3/0in9o9u5UM61ccxHNnKo/j827E6OHmdh6SjAp28YRHON5w1m ZCXcatNg==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAMH-00Cazj-Pv; Sat, 20 Aug 2022 00:21:01 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , linux-alpha@vger.kernel.org, Ivan Kokshaysky , Matt Turner , Richard Henderson Subject: [PATCH V3 03/11] alpha: Clean-up the panic notifier code Date: Fri, 19 Aug 2022 19:17:23 -0300 Message-Id: <20220819221731.480795-4-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The alpha panic notifier has some code issues, not following the conventions of other notifiers. Also, it might halt the machine but still it is set to run as early as possible, which doesn't seem to be a good idea. So, let's clean the code and set the notifier to run as the latest, following the same approach other architectures are doing - also, remove the unnecessary include of a header already included indirectly. Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Richard Henderson Reviewed-by: Petr Mladek Signed-off-by: Guilherme G. Piccoli --- V3: - No changes. V2: - Fixed rth email address; - Added Petr's review tag - thanks! arch/alpha/kernel/setup.c | 36 +++++++++++++++--------------------- 1 file changed, 15 insertions(+), 21 deletions(-) diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c index b4fbbba30aa2..d88bdf852753 100644 --- a/arch/alpha/kernel/setup.c +++ b/arch/alpha/kernel/setup.c @@ -41,19 +41,11 @@ #include #include #endif -#include #include #include #include #include -static int alpha_panic_event(struct notifier_block *, unsigned long, void *); -static struct notifier_block alpha_panic_block = { - alpha_panic_event, - NULL, - INT_MAX /* try to do it first */ -}; - #include #include #include @@ -435,6 +427,21 @@ static const struct sysrq_key_op srm_sysrq_reboot_op = { }; #endif +static int alpha_panic_event(struct notifier_block *this, + unsigned long event, void *ptr) +{ + /* If we are using SRM and serial console, just hard halt here. */ + if (alpha_using_srm && srmcons_output) + __halt(); + + return NOTIFY_DONE; +} + +static struct notifier_block alpha_panic_block = { + .notifier_call = alpha_panic_event, + .priority = INT_MIN, /* may not return, do it last */ +}; + void __init setup_arch(char **cmdline_p) { @@ -1427,19 +1434,6 @@ const struct seq_operations cpuinfo_op = { .show = show_cpuinfo, }; - -static int -alpha_panic_event(struct notifier_block *this, unsigned long event, void *ptr) -{ -#if 1 - /* FIXME FIXME FIXME */ - /* If we are using SRM and serial console, just hard halt here. */ - if (alpha_using_srm && srmcons_output) - __halt(); -#endif - return NOTIFY_DONE; -} - static __init int add_pcspkr(void) { struct platform_device *pd; From patchwork Fri Aug 19 22:17:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949302 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1B38C32771 for ; Fri, 19 Aug 2022 22:21:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241409AbiHSWVm (ORCPT ); Fri, 19 Aug 2022 18:21:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241296AbiHSWVl (ORCPT ); Fri, 19 Aug 2022 18:21:41 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D519D9D7B; Fri, 19 Aug 2022 15:21:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=I7PX0cg9hYhaVm6PvmjCfqAqk9/uhuAJh0bXjru0KJ8=; b=apxqB5qmqlzzY5vxuVHk/oybLg LGISEVYytiLSHzQM1NRBWL9ge/1BR3a5d4xyO3rwazWkQf6rO2OS/n67HAwdwBeLdPfOO/5+ptmdA nchEn0YnVSqzWI5LYJNJK99CREIoOfURPC5OxlOLbxBjzRqQBhWocnTVkl+50cp4hx2RdCPpm05KJ kQ0gUbNDHLN2x4iyxKfxMIsc6UVssvkUQWUb7CBWr3lNyq23EXMGdsgyAbCl6t5yNi3gsN1Pa8ZaO 6yXzHFVJTNoduFjBMFPFWJoF5WZJ0C44LC+4711S5JBo2OioK7T+35306PeO7vksSE6XS9+9PuVVj ZSO7++KA==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAMu-00Cb1Q-Tz; Sat, 20 Aug 2022 00:21:33 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , linux-um@lists.infradead.org, Anton Ivanov , Johannes Berg , Richard Weinberger Subject: [PATCH V3 04/11] um: Improve panic notifiers consistency and ordering Date: Fri, 19 Aug 2022 19:17:24 -0300 Message-Id: <20220819221731.480795-5-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently the panic notifiers from user mode linux don't follow the convention for most of the other notifiers present in the kernel (indentation, priority setting, numeric return). More important, the priorities could be improved, since it's a special case (userspace), hence we could run the notifiers earlier; user mode linux shouldn't care much with other panic notifiers but the ordering among the mconsole and arch notifier is important, given that the arch one effectively triggers a core dump. Fix that by running the mconsole notifier as the first panic notifier, followed by the architecture one (that coredumps). Cc: Anton Ivanov Cc: Johannes Berg Cc: Richard Weinberger Signed-off-by: Guilherme G. Piccoli V3: - No changes. V2: - Kept the notifier header to avoid implicit usage - thanks Johannes for the suggestion! --- arch/um/drivers/mconsole_kern.c | 7 +++---- arch/um/kernel/um_arch.c | 8 ++++---- 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c index 8ca67a692683..69af3ce8407a 100644 --- a/arch/um/drivers/mconsole_kern.c +++ b/arch/um/drivers/mconsole_kern.c @@ -846,13 +846,12 @@ static int notify_panic(struct notifier_block *self, unsigned long unused1, mconsole_notify(notify_socket, MCONSOLE_PANIC, message, strlen(message) + 1); - return 0; + return NOTIFY_DONE; } static struct notifier_block panic_exit_notifier = { - .notifier_call = notify_panic, - .next = NULL, - .priority = 1 + .notifier_call = notify_panic, + .priority = INT_MAX, /* run as soon as possible */ }; static int add_notifier(void) diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index e0de60e503b9..ae272878f692 100644 --- a/arch/um/kernel/um_arch.c +++ b/arch/um/kernel/um_arch.c @@ -247,13 +247,13 @@ static int panic_exit(struct notifier_block *self, unsigned long unused1, bust_spinlocks(0); uml_exitcode = 1; os_dump_core(); - return 0; + + return NOTIFY_DONE; } static struct notifier_block panic_exit_notifier = { - .notifier_call = panic_exit, - .next = NULL, - .priority = 0 + .notifier_call = panic_exit, + .priority = INT_MAX - 1, /* run as 2nd notifier, won't return */ }; void uml_finishsetup(void) From patchwork Fri Aug 19 22:17:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949308 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0C99C32772 for ; Fri, 19 Aug 2022 22:22:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241548AbiHSWWd (ORCPT ); Fri, 19 Aug 2022 18:22:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241454AbiHSWWc (ORCPT ); Fri, 19 Aug 2022 18:22:32 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8226610C832; Fri, 19 Aug 2022 15:22:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=c6bNbdkIvWKnXnfsb/cTBvGyb1ZPIuxweFGpqUPvTxs=; b=fvlRUlb5+jeq3HjwBCUDmjRGuw FilBZcRWvSvdyCdl3M9r1XaItVZZxUcdRx6Af1/Q/kzO3pO3UiFRTh3n5+uGQ32xPzqt87/q3NWjP dXBFA/8ttmKc3J8Ytpzvokb9t9WEPe5cB8SNibeXcLXWO/DmRho3BYUF3JGMV/40ycduXcMApaDPr BLxjodof8siwHC75VBwyv2EWv6whqmW1vmyIKVdla1tYuBU4tU80OZWtwW57TYjT9M5BR9Bd4H5TB NZ1XLPZJZ2ISvmifyTxMxbLzbSr7rBVPYpaVeSj8Yr1NajLCst5p2OrxgMYVp6BDav9peZIjRMnJp rYW0DQqQ==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPANk-00Cb3c-5Y; Sat, 20 Aug 2022 00:22:25 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , linux-parisc@vger.kernel.org, "James E.J. Bottomley" , Jeroen Roovers , Helge Deller Subject: [PATCH V3 05/11] parisc: Replace regular spinlock with spin_trylock on panic path Date: Fri, 19 Aug 2022 19:17:25 -0300 Message-Id: <20220819221731.480795-6-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The panic notifiers' callbacks execute in an atomic context, with interrupts/preemption disabled, and all CPUs not running the panic function are off, so it's very dangerous to wait on a regular spinlock, there's a risk of deadlock. Refactor the panic notifier of parisc/power driver to make use of spin_trylock - for that, we've added a second version of the soft-power function. Also, some comments were reorganized and trailing white spaces, useless header inclusion and blank lines were removed. Cc: "James E.J. Bottomley" Cc: Jeroen Roovers Acked-by: Helge Deller # parisc Signed-off-by: Guilherme G. Piccoli --- V3: - s/in/on as per Jeroen's suggestion - thanks! V2: - Added Helge's ACK - thanks! arch/parisc/include/asm/pdc.h | 1 + arch/parisc/kernel/firmware.c | 27 +++++++++++++++++++++++---- drivers/parisc/power.c | 17 ++++++++++------- 3 files changed, 34 insertions(+), 11 deletions(-) diff --git a/arch/parisc/include/asm/pdc.h b/arch/parisc/include/asm/pdc.h index b643092d4b98..7a106008e258 100644 --- a/arch/parisc/include/asm/pdc.h +++ b/arch/parisc/include/asm/pdc.h @@ -83,6 +83,7 @@ int pdc_do_firm_test_reset(unsigned long ftc_bitmap); int pdc_do_reset(void); int pdc_soft_power_info(unsigned long *power_reg); int pdc_soft_power_button(int sw_control); +int pdc_soft_power_button_panic(int sw_control); void pdc_io_reset(void); void pdc_io_reset_devices(void); int pdc_iodc_getc(void); diff --git a/arch/parisc/kernel/firmware.c b/arch/parisc/kernel/firmware.c index 6a7e315bcc2e..3b1f7641e3c9 100644 --- a/arch/parisc/kernel/firmware.c +++ b/arch/parisc/kernel/firmware.c @@ -1232,15 +1232,18 @@ int __init pdc_soft_power_info(unsigned long *power_reg) } /* - * pdc_soft_power_button - Control the soft power button behaviour - * @sw_control: 0 for hardware control, 1 for software control + * pdc_soft_power_button{_panic} - Control the soft power button behaviour + * @sw_control: 0 for hardware control, 1 for software control * * * This PDC function places the soft power button under software or * hardware control. - * Under software control the OS may control to when to allow to shut - * down the system. Under hardware control pressing the power button + * Under software control the OS may control to when to allow to shut + * down the system. Under hardware control pressing the power button * powers off the system immediately. + * + * The _panic version relies on spin_trylock to prevent deadlock + * on panic path. */ int pdc_soft_power_button(int sw_control) { @@ -1254,6 +1257,22 @@ int pdc_soft_power_button(int sw_control) return retval; } +int pdc_soft_power_button_panic(int sw_control) +{ + int retval; + unsigned long flags; + + if (!spin_trylock_irqsave(&pdc_lock, flags)) { + pr_emerg("Couldn't enable soft power button\n"); + return -EBUSY; /* ignored by the panic notifier */ + } + + retval = mem_pdc_call(PDC_SOFT_POWER, PDC_SOFT_POWER_ENABLE, __pa(pdc_result), sw_control); + spin_unlock_irqrestore(&pdc_lock, flags); + + return retval; +} + /* * pdc_io_reset - Hack to avoid overlapping range registers of Bridges devices. * Primarily a problem on T600 (which parisc-linux doesn't support) but diff --git a/drivers/parisc/power.c b/drivers/parisc/power.c index 456776bd8ee6..8512884de2cf 100644 --- a/drivers/parisc/power.c +++ b/drivers/parisc/power.c @@ -37,7 +37,6 @@ #include #include #include -#include #include #include #include @@ -175,16 +174,21 @@ static void powerfail_interrupt(int code, void *x) -/* parisc_panic_event() is called by the panic handler. - * As soon as a panic occurs, our tasklets above will not be - * executed any longer. This function then re-enables the - * soft-power switch and allows the user to switch off the system +/* + * parisc_panic_event() is called by the panic handler. + * + * As soon as a panic occurs, our tasklets above will not + * be executed any longer. This function then re-enables + * the soft-power switch and allows the user to switch off + * the system. We rely in pdc_soft_power_button_panic() + * since this version spin_trylocks (instead of regular + * spinlock), preventing deadlocks on panic path. */ static int parisc_panic_event(struct notifier_block *this, unsigned long event, void *ptr) { /* re-enable the soft-power switch */ - pdc_soft_power_button(0); + pdc_soft_power_button_panic(0); return NOTIFY_DONE; } @@ -193,7 +197,6 @@ static struct notifier_block parisc_panic_block = { .priority = INT_MAX, }; - static int __init power_init(void) { unsigned long ret; From patchwork Fri Aug 19 22:17:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949309 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE88BC32773 for ; Fri, 19 Aug 2022 22:22:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241761AbiHSWW5 (ORCPT ); Fri, 19 Aug 2022 18:22:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241663AbiHSWW4 (ORCPT ); Fri, 19 Aug 2022 18:22:56 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B01F10E7A9; Fri, 19 Aug 2022 15:22:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=bzGFkTIN1eV205ENSSxwAqghJ7GC09NvM0cYNIKPVVQ=; b=AzhVCmuSU/fFLe+lgazLXq461g rWlTcBz9vzc3hztKuV11gnmPJswp6BdDA2jApg28Fy+Uo2w61g7jZlJSXeOqTAQYbVZxSGy9JipuB 6w7S/xilAxGAmXMMVnsYag9AJ+2gUD82er23HSQWvozHBeiRK2SK9iQGsZSKhn9yyPpV8Pco+4beC LVCpCvRAuYF1FRW9z15Q1dRf5AvSGwUDCjCSlsSDONAkH3xZJOPZl/xFtZVkciKJXIQWlQoy0I/lV RZgBWuBnkOilm2cYi45ZELRyofmCUHbAX09+35QI1M15oTbM/cFqG5awxE9GY4iottk4EyI2EzvjL nk7fIA2w==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAO6-00Cb4O-O3; Sat, 20 Aug 2022 00:22:51 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , Sergei Shtylyov Subject: [PATCH V3 06/11] tracing: Improve panic/die notifiers Date: Fri, 19 Aug 2022 19:17:26 -0300 Message-Id: <20220819221731.480795-7-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently the tracing dump_on_oops feature is implemented through separate notifiers, one for die/oops and the other for panic; given they have the same functionality, let's unify them. Also improve the function comment and change the priority of the notifier to make it execute earlier, avoiding showing useless trace data (like the callback names for the other notifiers); finally, we also removed an unnecessary header inclusion. Cc: Petr Mladek Cc: Sergei Shtylyov Cc: Steven Rostedt Signed-off-by: Guilherme G. Piccoli Acked-by: Steven Rostedt (Google) --- V3: - Removed goto usage, as per Steven suggestion (thanks!). V2: - Different approach; instead of using IDs to distinguish die and panic events, rely on address comparison like other notifiers do and as per Petr's suggestion; - Removed ACK from Steven since the code changed. kernel/trace/trace.c | 55 ++++++++++++++++++++++---------------------- 1 file changed, 27 insertions(+), 28 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d3005279165d..0bacdbcb132f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -19,7 +19,6 @@ #include #include #include -#include #include #include #include @@ -9776,40 +9775,40 @@ static __init int tracer_init_tracefs(void) fs_initcall(tracer_init_tracefs); -static int trace_panic_handler(struct notifier_block *this, - unsigned long event, void *unused) -{ - if (ftrace_dump_on_oops) - ftrace_dump(ftrace_dump_on_oops); - return NOTIFY_OK; -} +static int trace_die_panic_handler(struct notifier_block *self, + unsigned long ev, void *unused); static struct notifier_block trace_panic_notifier = { - .notifier_call = trace_panic_handler, - .next = NULL, - .priority = 150 /* priority: INT_MAX >= x >= 0 */ + .notifier_call = trace_die_panic_handler, + .priority = INT_MAX - 1, }; -static int trace_die_handler(struct notifier_block *self, - unsigned long val, - void *data) -{ - switch (val) { - case DIE_OOPS: - if (ftrace_dump_on_oops) - ftrace_dump(ftrace_dump_on_oops); - break; - default: - break; - } - return NOTIFY_OK; -} - static struct notifier_block trace_die_notifier = { - .notifier_call = trace_die_handler, - .priority = 200 + .notifier_call = trace_die_panic_handler, + .priority = INT_MAX - 1, }; +/* + * The idea is to execute the following die/panic callback early, in order + * to avoid showing irrelevant information in the trace (like other panic + * notifier functions); we are the 2nd to run, after hung_task/rcu_stall + * warnings get disabled (to prevent potential log flooding). + */ +static int trace_die_panic_handler(struct notifier_block *self, + unsigned long ev, void *unused) +{ + if (!ftrace_dump_on_oops) + return NOTIFY_DONE; + + /* The die notifier requires DIE_OOPS to trigger */ + if (self == &trace_die_notifier && ev != DIE_OOPS) + return NOTIFY_DONE; + + ftrace_dump(ftrace_dump_on_oops); + + return NOTIFY_DONE; +} + /* * printk is set to max of 1024, we really don't need it that big. * Nothing should be printing 1000 characters anyway. From patchwork Fri Aug 19 22:17:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949310 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79B70C32772 for ; Fri, 19 Aug 2022 22:23:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241906AbiHSWXe (ORCPT ); Fri, 19 Aug 2022 18:23:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241767AbiHSWXd (ORCPT ); Fri, 19 Aug 2022 18:23:33 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4CEED2CDC8; Fri, 19 Aug 2022 15:23:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=d2an8K4S3oBRBmk7SIJDz4Oai1o8VvWFhnH8gpD08U0=; b=X2+kGd13kauJptBzv6orQ1U7yS 4aVfkn5eFTKuYn33XLrObdbdfBscRW7PnPpTi00KjX722oTJFFbDGBByOFk/diOtlqyJUfXp1qqtk wdAyoKW3PdYKCTsCYnvnraOEqwCd466jDzHdiLOwLKF9ZjNoUljXl9a8OK3JS3DA64x+It+MtEgjo 9j46jITNnxNXwQM8p6iXaD+6u+VxqJqBPZbsVtVKQDuWHrqQ2/urSChnRWiPaMvc2L+ukkn4Fmyax j1lFef3s95ENI6oiTnHSrbeqhX4dTAauX2TwiB5awED4vpx4s2jm8I3rnXNRpHJaRpI5R0QmdmdLU O+2sMEDw==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAOh-00Cb6O-5U; Sat, 20 Aug 2022 00:23:25 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , Arjan van de Ven , Cong Wang , Sebastian Andrzej Siewior , Valentin Schneider , Xiaoming Ni Subject: [PATCH V3 07/11] notifiers: Add tracepoints to the notifiers infrastructure Date: Fri, 19 Aug 2022 19:17:27 -0300 Message-Id: <20220819221731.480795-8-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently there is no way to show the callback names for registered, unregistered or executed notifiers. This is very useful for debug purposes, hence add this functionality here in the form of notifiers' tracepoints, one per operation. Cc: Arjan van de Ven Cc: Cong Wang Cc: Sebastian Andrzej Siewior Cc: Steven Rostedt Cc: Valentin Schneider Cc: Xiaoming Ni Signed-off-by: Guilherme G. Piccoli --- V3: - Yet another major change - thanks to Arjan's great suggestion, refactored the code to make use of tracepoints instead of guarding the output with a Kconfig debug setting. V2: - Major improvement thanks to the great idea from Xiaoming - changed all the ksym wheel reinvention to printk %ps modifier; - Instead of ifdefs, using IS_ENABLED() - thanks Steven. - Removed an unlikely() hint on debug path. include/trace/events/notifiers.h | 69 ++++++++++++++++++++++++++++++++ kernel/notifier.c | 6 +++ 2 files changed, 75 insertions(+) create mode 100644 include/trace/events/notifiers.h diff --git a/include/trace/events/notifiers.h b/include/trace/events/notifiers.h new file mode 100644 index 000000000000..e8f30631aef5 --- /dev/null +++ b/include/trace/events/notifiers.h @@ -0,0 +1,69 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM notifiers + +#if !defined(_TRACE_NOTIFIERS_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_NOTIFIERS_H + +#include + +DECLARE_EVENT_CLASS(notifiers_info, + + TP_PROTO(void *cb), + + TP_ARGS(cb), + + TP_STRUCT__entry( + __field(void *, cb) + ), + + TP_fast_assign( + __entry->cb = cb; + ), + + TP_printk("%ps", __entry->cb) +); + +/* + * notifiers_register - called upon notifier callback registration + * + * @cb: callback pointer + * + */ +DEFINE_EVENT(notifiers_info, notifiers_register, + + TP_PROTO(void *cb), + + TP_ARGS(cb) +); + +/* + * notifiers_unregister - called upon notifier callback unregistration + * + * @cb: callback pointer + * + */ +DEFINE_EVENT(notifiers_info, notifiers_unregister, + + TP_PROTO(void *cb), + + TP_ARGS(cb) +); + +/* + * notifiers_run - called upon notifier callback execution + * + * @cb: callback pointer + * + */ +DEFINE_EVENT(notifiers_info, notifiers_run, + + TP_PROTO(void *cb), + + TP_ARGS(cb) +); + +#endif /* _TRACE_NOTIFIERS_H */ + +/* This part must be outside protection */ +#include diff --git a/kernel/notifier.c b/kernel/notifier.c index 0d5bd62c480e..2f2783f59a31 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -7,6 +7,9 @@ #include #include +#define CREATE_TRACE_POINTS +#include + /* * Notifier list for kernel code which wants to be called * at shutdown. This is used to stop any idling DMA operations @@ -37,6 +40,7 @@ static int notifier_chain_register(struct notifier_block **nl, } n->next = *nl; rcu_assign_pointer(*nl, n); + trace_notifiers_register((void*)n->notifier_call); return 0; } @@ -46,6 +50,7 @@ static int notifier_chain_unregister(struct notifier_block **nl, while ((*nl) != NULL) { if ((*nl) == n) { rcu_assign_pointer(*nl, n->next); + trace_notifiers_unregister((void*)n->notifier_call); return 0; } nl = &((*nl)->next); @@ -84,6 +89,7 @@ static int notifier_call_chain(struct notifier_block **nl, continue; } #endif + trace_notifiers_run((void*)nb->notifier_call); ret = nb->notifier_call(nb, val, v); if (nr_calls) From patchwork Fri Aug 19 22:17:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949311 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2558FC32773 for ; Fri, 19 Aug 2022 22:24:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242033AbiHSWYA (ORCPT ); Fri, 19 Aug 2022 18:24:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241975AbiHSWXy (ORCPT ); Fri, 19 Aug 2022 18:23:54 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76D9B23BD1; Fri, 19 Aug 2022 15:23:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=OonmUPZkO/emCOphZ8VnLPwYmag4wEjaMQk7IMB+RMQ=; b=frivb87m1aODDLexRXHjILEpy0 zypuxM1lUa2+Sde0ChP8r+SpXKZTYYQ06rsm4azbLcf835GhtiU/63eTRWcbzZyjLucvdKKHJYKiK /euCL6+qpMh2bq+mDBCmd4zfYMRfG4Tqf1qA8tyF9Sf9mTKWE49sFBT6zlM+mWR7kHQzFnNnWU6MW lkll9FniO4rDprJKDPgb+tUp2okPeMrFiVLU/alXFetoW59OAkLnidfuhStQMFD628z2AmR0v5dqg u9NF7VPoqZwVRcG9G6dqJ9Zqmry2mF8HYNj1eMF0SH2Nd3PIvrPYCM3Wwvafygev10hLlqXwn+n1L GJahVPlA==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAP0-00Cb74-3H; Sat, 20 Aug 2022 00:23:47 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , linux-edac@vger.kernel.org, Tony Luck , Dinh Nguyen Subject: [PATCH V3 08/11] EDAC/altera: Skip the panic notifier if kdump is loaded Date: Fri, 19 Aug 2022 19:17:28 -0300 Message-Id: <20220819221731.480795-9-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The altera_edac panic notifier performs some data collection with regards errors detected; such code relies in the regmap layer to perform reads/writes, so the code is abstracted and there is some risk level to execute that, since the panic path runs in atomic context, with interrupts/preemption and secondary CPUs disabled. Users want the information collected in this panic notifier though, so in order to balance the risk/benefit, let's skip the altera panic notifier if kdump is loaded. While at it, remove a useless header and encompass a macro inside the sole ifdef block it is used. Cc: Borislav Petkov Cc: Petr Mladek Cc: Tony Luck Acked-by: Dinh Nguyen Signed-off-by: Guilherme G. Piccoli --- V3: - added the ack tag from Dinh - thanks! - had a good discussion with Boris about that in V2 [0], hopefully we can continue and reach a consensus in this V3. [0] https://lore.kernel.org/lkml/46137c67-25b4-6657-33b7-cffdc7afc0d7@igalia.com/ V2: - new patch, based on the discussion in [1]. [1] https://lore.kernel.org/lkml/62a63fc2-346f-f375-043a-fa21385279df@igalia.com/ drivers/edac/altera_edac.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c index e7e8e624a436..741fe5539154 100644 --- a/drivers/edac/altera_edac.c +++ b/drivers/edac/altera_edac.c @@ -16,7 +16,6 @@ #include #include #include -#include #include #include #include @@ -24,6 +23,7 @@ #include #include #include +#include #include #include "altera_edac.h" @@ -2063,22 +2063,30 @@ static const struct irq_domain_ops a10_eccmgr_ic_ops = { }; /************** Stratix 10 EDAC Double Bit Error Handler ************/ -#define to_a10edac(p, m) container_of(p, struct altr_arria10_edac, m) - #ifdef CONFIG_64BIT /* panic routine issues reboot on non-zero panic_timeout */ extern int panic_timeout; +#define to_a10edac(p, m) container_of(p, struct altr_arria10_edac, m) + /* * The double bit error is handled through SError which is fatal. This is * called as a panic notifier to printout ECC error info as part of the panic. + * + * Notice that if kdump is set, we take the risk avoidance approach and + * skip the notifier, given that users are expected to have access to a + * full vmcore. */ static int s10_edac_dberr_handler(struct notifier_block *this, unsigned long event, void *ptr) { - struct altr_arria10_edac *edac = to_a10edac(this, panic_notifier); + struct altr_arria10_edac *edac; int err_addr, dberror; + if (kexec_crash_loaded()) + return NOTIFY_DONE; + + edac = to_a10edac(this, panic_notifier); regmap_read(edac->ecc_mgr_map, S10_SYSMGR_ECC_INTSTAT_DERR_OFST, &dberror); regmap_write(edac->ecc_mgr_map, S10_SYSMGR_UE_VAL_OFST, dberror); From patchwork Fri Aug 19 22:17:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949312 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB45CC32773 for ; Fri, 19 Aug 2022 22:24:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242079AbiHSWYh (ORCPT ); Fri, 19 Aug 2022 18:24:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241975AbiHSWYg (ORCPT ); Fri, 19 Aug 2022 18:24:36 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 38FD658DDA; Fri, 19 Aug 2022 15:24:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=MGMXDXJrezdc1pzNEVN7nSEhPhS4C9dgmc2AyYtjZfA=; b=FbAGBcwIbhblFEXoZjDRiavCoW rOM6d1mKWp8XDb/6WUDmTwquPgkM6xyMHXBCSzttyCQrfX7vN6kajCpBdz/tchH4k0Aib0GMapjcs /JdD3YBIhegAsRJv8KNgVEby2v+Qhqkj1nDtA5gZwKrgfTxe+9+r4AfIEFmXomwWIuDalNtq8ZCIx uwARMZ5QX41wMBmaaqFQdzjUolT4Lv3Q9qQezK/HQxHaj2hQ49dMkdmUEF99RJg++F4Gow1LbiA9x Imt73H5qWzsYCko7ffacQND8Lp2Ogj4Y5llzsrzqmurOrY0HW0FF9iiXUrOQVG3/nQlQdEmJTNDdu qoKPe80Q==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAPh-00Cb8p-Gg; Sat, 20 Aug 2022 00:24:28 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , Andrea Parri , Dexuan Cui , Haiyang Zhang , "K. Y. Srinivasan" , Stephen Hemminger , Tianyu Lan , Wei Liu Subject: [PATCH V3 09/11] video/hyperv_fb: Avoid taking busy spinlock on panic path Date: Fri, 19 Aug 2022 19:17:29 -0300 Message-Id: <20220819221731.480795-10-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The Hyper-V framebuffer code registers a panic notifier in order to try updating its fbdev if the kernel crashed. The notifier callback is straightforward, but it calls the vmbus_sendpacket() routine eventually, and such function takes a spinlock for the ring buffer operations. Panic path runs in atomic context, with local interrupts and preemption disabled, and all secondary CPUs shutdown. That said, taking a spinlock might cause a lockup if a secondary CPU was disabled with such lock taken. Fix it here by checking if the ring buffer spinlock is busy on Hyper-V framebuffer panic notifier; if so, bail-out avoiding the potential lockup scenario. Cc: Andrea Parri (Microsoft) Cc: Dexuan Cui Cc: Haiyang Zhang Cc: "K. Y. Srinivasan" Cc: Michael Kelley Cc: Stephen Hemminger Cc: Tianyu Lan Cc: Wei Liu Tested-by: Fabio A M Martins Signed-off-by: Guilherme G. Piccoli Reviewed-by: Michael Kelley --- V3: - simplified the code based on Michael's suggestion - thanks! V2: - new patch, based on the discussion in [0]. [0] https://lore.kernel.org/lkml/2787b476-6366-1c83-db80-0393da417497@igalia.com/ drivers/hv/ring_buffer.c | 13 +++++++++++++ drivers/video/fbdev/hyperv_fb.c | 8 +++++++- include/linux/hyperv.h | 2 ++ 3 files changed, 22 insertions(+), 1 deletion(-) diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 59a4aa86d1f3..c6692fd5ab15 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -280,6 +280,19 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) ring_info->pkt_buffer_size = 0; } +/* + * Check if the ring buffer spinlock is available to take or not; used on + * atomic contexts, like panic path (see the Hyper-V framebuffer driver). + */ + +bool hv_ringbuffer_spinlock_busy(struct vmbus_channel *channel) +{ + struct hv_ring_buffer_info *rinfo = &channel->outbound; + + return spin_is_locked(&rinfo->ring_lock); +} +EXPORT_SYMBOL_GPL(hv_ringbuffer_spinlock_busy); + /* Write to the ring buffer. */ int hv_ringbuffer_write(struct vmbus_channel *channel, const struct kvec *kv_list, u32 kv_count, diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c index 886c564787f1..e1b65a01fb96 100644 --- a/drivers/video/fbdev/hyperv_fb.c +++ b/drivers/video/fbdev/hyperv_fb.c @@ -783,12 +783,18 @@ static void hvfb_ondemand_refresh_throttle(struct hvfb_par *par, static int hvfb_on_panic(struct notifier_block *nb, unsigned long e, void *p) { + struct hv_device *hdev; struct hvfb_par *par; struct fb_info *info; par = container_of(nb, struct hvfb_par, hvfb_panic_nb); - par->synchronous_fb = true; info = par->info; + hdev = device_to_hv_device(info->device); + + if (hv_ringbuffer_spinlock_busy(hdev->channel)) + return NOTIFY_DONE; + + par->synchronous_fb = true; if (par->need_docopy) hvfb_docopy(par, 0, dio_fb_size); synthvid_update(info, 0, 0, INT_MAX, INT_MAX); diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index 3b42264333ef..646f1da9f27e 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -1341,6 +1341,8 @@ struct hv_ring_buffer_debug_info { int hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, struct hv_ring_buffer_debug_info *debug_info); +bool hv_ringbuffer_spinlock_busy(struct vmbus_channel *channel); + /* Vmbus interface */ #define vmbus_driver_register(driver) \ __vmbus_driver_register(driver, THIS_MODULE, KBUILD_MODNAME) From patchwork Fri Aug 19 22:17:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949313 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2816C32789 for ; Fri, 19 Aug 2022 22:26:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242164AbiHSW0p (ORCPT ); Fri, 19 Aug 2022 18:26:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241975AbiHSW0n (ORCPT ); Fri, 19 Aug 2022 18:26:43 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0056F10A74E; Fri, 19 Aug 2022 15:26:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=JM9Drna9qCkuXYcgitMbKoCXFed7NeXSxXsah2tjvgg=; b=p6K24F8rtU3d2Ldfz0e5oJ9YuZ +KS6jNUq85CuFdFWjmJeia7WQ3YSDoUhro8F0PDVzyBBqiRkw6w91u7Zss9p2XNWqe0CRCv3WXtNO D/13l+mEenSy7LUNO882WVlwkbVHvEs9j9aU0jFdJYIUXJeoKHmpMZmuASj4VbQ+yV4eAhfdzt3XA rQX+NTVhKPJEz3Uu1BbUVYPCLApghZIKc0252OOOT/VdJhFXJXobcNY1VuDF5AHGkEY6+9gZFx7vM +LzLXSMwkxnG//aM2mgzIowrUrI3X7MRE3ah9WkBAGGMBStW7TJdj3Rl1E6THySNikKx/1E8Wi4dn J2J1lH+A==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPARm-00CbEo-54; Sat, 20 Aug 2022 00:26:36 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" , Andrea Parri , Dexuan Cui , Haiyang Zhang , "K. Y. Srinivasan" , Stephen Hemminger , Tianyu Lan , Wei Liu Subject: [PATCH V3 10/11] drivers/hv/vmbus, video/hyperv_fb: Untangle and refactor Hyper-V panic notifiers Date: Fri, 19 Aug 2022 19:17:30 -0300 Message-Id: <20220819221731.480795-11-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently Hyper-V guests are among the most relevant users of the panic infrastructure, like panic notifiers, kmsg dumpers, etc. The reasons rely both in cleaning-up procedures (closing hypervisor <-> guest connection, disabling some paravirtualized timer) as well as to data collection (sending panic information to the hypervisor) and framebuffer management. The thing is: some notifiers are related to others, ordering matters, some functionalities are duplicated and there are lots of conditionals behind sending panic information to the hypervisor. As part of an effort to clean-up the panic notifiers mechanism and better document things, we hereby address some of the issues/complexities of Hyper-V panic handling through the following changes: (a) We have die and panic notifiers on vmbus_drv.c and both have goals of sending panic information to the hypervisor, though the panic notifier is also responsible for a cleaning-up procedure. This commit clears the code by splitting the panic notifier in two, one for closing the vmbus connection whereas the other is only for sending panic info to hypervisor. With that, it was possible to merge the die and panic notifiers in a single/well-documented function, and clear some conditional complexities on sending such information to the hypervisor. (b) There is a Hyper-V framebuffer panic notifier, which relies in doing a vmbus operation that demands a valid connection. So, we must order this notifier with the panic notifier from vmbus_drv.c, to guarantee that the framebuffer code executes before the vmbus connection is unloaded. Also, this commit removes a useless header. Although there is code rework and re-ordering, we expect that this change has no functional regressions but instead optimize the path and increase panic reliability on Hyper-V. This was tested on Hyper-V with success. Cc: Andrea Parri (Microsoft) Cc: Dexuan Cui Cc: Haiyang Zhang Cc: "K. Y. Srinivasan" Cc: Petr Mladek Cc: Stephen Hemminger Cc: Tianyu Lan Cc: Wei Liu Reviewed-by: Michael Kelley Tested-by: Fabio A M Martins Signed-off-by: Guilherme G. Piccoli Tested-by: Michael Kelley --- V3: - Added Michael's review tag - thanks! V2: - Unfortunately we cannot rely in the crash shutdown (custom) handler to perform the vmbus unload - arm64 architecture doesn't have this "feature" [0]. So, in V2 we kept the notifier behavior and always unload the vmbus connection, no matter what - thanks Michael for pointing that; - Removed the Fixes tags as per Michael suggestion; - As per Petr suggestion, we abandoned the idea of distinguish among notifiers using an id - so, in V2 we rely in the old and good address comparison for that. Thanks Petr for the enriching discussion! [0] https://lore.kernel.org/lkml/427a8277-49f0-4317-d6c3-4a15d7070e55@igalia.com/ drivers/hv/vmbus_drv.c | 109 +++++++++++++++++++------------- drivers/video/fbdev/hyperv_fb.c | 8 +++ 2 files changed, 74 insertions(+), 43 deletions(-) diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 23c680d1a0f5..0a77e2bb0b70 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -25,7 +25,6 @@ #include #include -#include #include #include #include @@ -69,53 +68,74 @@ static int hyperv_report_reg(void) return !sysctl_record_panic_msg || !hv_panic_page; } -static int hyperv_panic_event(struct notifier_block *nb, unsigned long val, +/* + * The panic notifier below is responsible solely for unloading the + * vmbus connection, which is necessary in a panic event. + * + * Notice an intrincate relation of this notifier with Hyper-V + * framebuffer panic notifier exists - we need vmbus connection alive + * there in order to succeed, so we need to order both with each other + * [see hvfb_on_panic()] - this is done using notifiers' priorities. + */ +static int hv_panic_vmbus_unload(struct notifier_block *nb, unsigned long val, void *args) +{ + vmbus_initiate_unload(true); + return NOTIFY_DONE; +} +static struct notifier_block hyperv_panic_vmbus_unload_block = { + .notifier_call = hv_panic_vmbus_unload, + .priority = INT_MIN + 1, /* almost the latest one to execute */ +}; + +static int hv_die_panic_notify_crash(struct notifier_block *self, + unsigned long val, void *args); + +static struct notifier_block hyperv_die_report_block = { + .notifier_call = hv_die_panic_notify_crash, +}; +static struct notifier_block hyperv_panic_report_block = { + .notifier_call = hv_die_panic_notify_crash, +}; + +/* + * The following callback works both as die and panic notifier; its + * goal is to provide panic information to the hypervisor unless the + * kmsg dumper is used [see hv_kmsg_dump()], which provides more + * information but isn't always available. + * + * Notice that both the panic/die report notifiers are registered only + * if we have the capability HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE set. + */ +static int hv_die_panic_notify_crash(struct notifier_block *self, + unsigned long val, void *args) { struct pt_regs *regs; + bool is_die; - vmbus_initiate_unload(true); - - /* - * Hyper-V should be notified only once about a panic. If we will be - * doing hv_kmsg_dump() with kmsg data later, don't do the notification - * here. - */ - if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE - && hyperv_report_reg()) { + /* Don't notify Hyper-V unless we have a die oops event or panic. */ + if (self == &hyperv_panic_report_block) { + is_die = false; regs = current_pt_regs(); - hyperv_report_panic(regs, val, false); + } else { /* die event */ + if (val != DIE_OOPS) + return NOTIFY_DONE; + + is_die = true; + regs = ((struct die_args *)args)->regs; } - return NOTIFY_DONE; -} - -static int hyperv_die_event(struct notifier_block *nb, unsigned long val, - void *args) -{ - struct die_args *die = args; - struct pt_regs *regs = die->regs; - - /* Don't notify Hyper-V if the die event is other than oops */ - if (val != DIE_OOPS) - return NOTIFY_DONE; /* - * Hyper-V should be notified only once about a panic. If we will be - * doing hv_kmsg_dump() with kmsg data later, don't do the notification - * here. + * Hyper-V should be notified only once about a panic/die. If we will + * be calling hv_kmsg_dump() later with kmsg data, don't do the + * notification here. */ if (hyperv_report_reg()) - hyperv_report_panic(regs, val, true); + hyperv_report_panic(regs, val, is_die); + return NOTIFY_DONE; } -static struct notifier_block hyperv_die_block = { - .notifier_call = hyperv_die_event, -}; -static struct notifier_block hyperv_panic_block = { - .notifier_call = hyperv_panic_event, -}; - static const char *fb_mmio_name = "fb_range"; static struct resource *fb_mmio; static struct resource *hyperv_mmio; @@ -1538,16 +1558,17 @@ static int vmbus_bus_init(void) if (hyperv_crash_ctl & HV_CRASH_CTL_CRASH_NOTIFY_MSG) hv_kmsg_dump_register(); - register_die_notifier(&hyperv_die_block); + register_die_notifier(&hyperv_die_report_block); + atomic_notifier_chain_register(&panic_notifier_list, + &hyperv_panic_report_block); } /* - * Always register the panic notifier because we need to unload - * the VMbus channel connection to prevent any VMbus - * activity after the VM panics. + * Always register the vmbus unload panic notifier because we + * need to shut the VMbus channel connection on panic. */ atomic_notifier_chain_register(&panic_notifier_list, - &hyperv_panic_block); + &hyperv_panic_vmbus_unload_block); vmbus_request_offers(); @@ -2776,15 +2797,17 @@ static void __exit vmbus_exit(void) if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) { kmsg_dump_unregister(&hv_kmsg_dumper); - unregister_die_notifier(&hyperv_die_block); + unregister_die_notifier(&hyperv_die_report_block); + atomic_notifier_chain_unregister(&panic_notifier_list, + &hyperv_panic_report_block); } /* - * The panic notifier is always registered, hence we should + * The vmbus panic notifier is always registered, hence we should * also unconditionally unregister it here as well. */ atomic_notifier_chain_unregister(&panic_notifier_list, - &hyperv_panic_block); + &hyperv_panic_vmbus_unload_block); free_page((unsigned long)hv_panic_page); unregister_sysctl_table(hv_ctl_table_hdr); diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c index e1b65a01fb96..9234d31d4305 100644 --- a/drivers/video/fbdev/hyperv_fb.c +++ b/drivers/video/fbdev/hyperv_fb.c @@ -1216,7 +1216,15 @@ static int hvfb_probe(struct hv_device *hdev, par->fb_ready = true; par->synchronous_fb = false; + + /* + * We need to be sure this panic notifier runs _before_ the + * vmbus disconnect, so order it by priority. It must execute + * before the function hv_panic_vmbus_unload() [drivers/hv/vmbus_drv.c], + * which is almost at the end of list, with priority = INT_MIN + 1. + */ par->hvfb_panic_nb.notifier_call = hvfb_on_panic; + par->hvfb_panic_nb.priority = INT_MIN + 10, atomic_notifier_chain_register(&panic_notifier_list, &par->hvfb_panic_nb); From patchwork Fri Aug 19 22:17:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 12949319 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 620A9C32789 for ; Fri, 19 Aug 2022 22:27:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242222AbiHSW1I (ORCPT ); Fri, 19 Aug 2022 18:27:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242215AbiHSW1G (ORCPT ); Fri, 19 Aug 2022 18:27:06 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26700112331; Fri, 19 Aug 2022 15:27:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=bwBb3Wqkav6yGYTcSOKgHtTuFq6y9W8T2JmU+7U+WFw=; b=FPIhhlYmbA7Ekd0SbUE79tFQuq sD7VF0K26UYnuYDL/GpMEqpIndV32PKyaEf3+hLJtzhpUgMvejS6b08pKh0EDi1XNiocxGbRtpA5A dFRzLqe44KDmWV0NpqXAEy1n9hNo/BgL5WhLnaSSGLFMIhjwuIGgJ6Y8f+5KmTj3+M6XIeLsawto5 3LG9bcijhNeCZXf5dfWrlTxTUd8zrf3C8miCJGksaHHYASbw37n3YqclWfd35S5tONxjbfrzriRon GjsDoQlXa4+rQ3fkp03slSd7Di/jYXir/5aJghvsv9DM/e3vg/LUwdJt7Y35Nl7voPZEOsFUMntUi zWl13YyA==; Received: from [179.232.144.59] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oPAS8-00CbFM-Vn; Sat, 20 Aug 2022 00:26:59 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, xuqiang36@huawei.com, "Guilherme G. Piccoli" Subject: [PATCH V3 11/11] panic: Fixes the panic_print NMI backtrace setting Date: Fri, 19 Aug 2022 19:17:31 -0300 Message-Id: <20220819221731.480795-12-gpiccoli@igalia.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819221731.480795-1-gpiccoli@igalia.com> References: <20220819221731.480795-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Commit 8d470a45d1a6 ("panic: add option to dump all CPUs backtraces in panic_print") introduced a setting for the "panic_print" kernel parameter to allow users to request a NMI backtrace on panic. Problem is that the panic_print handling happens after the secondary CPUs are already disabled, hence this option ended-up being kind of a no-op - kernel skips the NMI trace in idling CPUs, which is the case of offline CPUs. Fix it by checking the NMI backtrace bit in the panic_print prior to the CPU disabling function. Fixes: 8d470a45d1a6 ("panic: add option to dump all CPUs backtraces in panic_print") Cc: Feng Tang Cc: Petr Mladek Signed-off-by: Guilherme G. Piccoli --- V3: - No changes. V2: - new patch, there was no V1 of this one. Hi folks, thanks upfront for reviews. This is a new patch, fixing an issue I found in my tests, so I shoved it into this fixes series. Notice that while at it, I got rid of the "crash_kexec_post_notifiers" local copy in panic(). This was introduced by commit b26e27ddfd2a ("kexec: use core_param for crash_kexec_post_notifiers boot option"), but it is not clear from comments or commit message why this local copy is required. My understanding is that it's a mechanism to prevent some concurrency, in case some other CPU modify this variable while panic() is running. I find it very unlikely, hence I removed it - but if people consider this copy needed, I can respin this patch and keep it, even providing a comment about that, in order to be explict about its need. Let me know your thoughts! Cheers, Guilherme kernel/panic.c | 47 +++++++++++++++++++++++++++-------------------- 1 file changed, 27 insertions(+), 20 deletions(-) diff --git a/kernel/panic.c b/kernel/panic.c index c6eb8f8db0c0..b025a8f21c17 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -180,9 +180,6 @@ static void panic_print_sys_info(bool console_flush) return; } - if (panic_print & PANIC_PRINT_ALL_CPU_BT) - trigger_all_cpu_backtrace(); - if (panic_print & PANIC_PRINT_TASK_INFO) show_state(); @@ -199,6 +196,30 @@ static void panic_print_sys_info(bool console_flush) ftrace_dump(DUMP_ALL); } +/* + * Helper that triggers the NMI backtrace (if set in panic_print) + * and then performs the secondary CPUs shutdown - we cannot have + * the NMI backtrace after the CPUs are off! + */ +static void panic_other_cpus_shutdown(void) +{ + if (panic_print & PANIC_PRINT_ALL_CPU_BT) + trigger_all_cpu_backtrace(); + + /* + * Note that smp_send_stop() is the usual SMP shutdown function, + * which unfortunately may not be hardened to work in a panic + * situation. If we want to do crash dump after notifier calls + * and kmsg_dump, we will need architecture dependent extra + * bits in addition to stopping other CPUs, hence we rely on + * crash_smp_send_stop() for that. + */ + if (!crash_kexec_post_notifiers) + smp_send_stop(); + else + crash_smp_send_stop(); +} + /** * panic - halt the system * @fmt: The text string to print @@ -214,7 +235,6 @@ void panic(const char *fmt, ...) long i, i_next = 0, len; int state = 0; int old_cpu, this_cpu; - bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; if (panic_on_warn) { /* @@ -289,23 +309,10 @@ void panic(const char *fmt, ...) * * Bypass the panic_cpu check and call __crash_kexec directly. */ - if (!_crash_kexec_post_notifiers) { + if (!crash_kexec_post_notifiers) __crash_kexec(NULL); - /* - * Note smp_send_stop is the usual smp shutdown function, which - * unfortunately means it may not be hardened to work in a - * panic situation. - */ - smp_send_stop(); - } else { - /* - * If we want to do crash dump after notifier calls and - * kmsg_dump, we will need architecture dependent extra - * works in addition to stopping other CPUs. - */ - crash_smp_send_stop(); - } + panic_other_cpus_shutdown(); /* * Run any panic handlers, including those that might need to @@ -326,7 +333,7 @@ void panic(const char *fmt, ...) * * Bypass the panic_cpu check and call __crash_kexec directly. */ - if (_crash_kexec_post_notifiers) + if (crash_kexec_post_notifiers) __crash_kexec(NULL); #ifdef CONFIG_VT