From patchwork Wed Dec 9 13:21:03 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Petr Mladek X-Patchwork-Id: 7808611 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 121309F350 for ; Wed, 9 Dec 2015 13:24:16 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4F8D620460 for ; Wed, 9 Dec 2015 13:24:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 71A0820499 for ; Wed, 9 Dec 2015 13:24:14 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1a6ehU-0007AO-O0; Wed, 09 Dec 2015 13:22:32 +0000 Received: from mx2.suse.de ([195.135.220.15]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1a6egs-0006nK-Lw for linux-arm-kernel@lists.infradead.org; Wed, 09 Dec 2015 13:21:57 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 5A010AD59; Wed, 9 Dec 2015 13:21:33 +0000 (UTC) From: Petr Mladek To: Andrew Morton Subject: [PATCH v3 2/4] printk/nmi: Use IRQ work only when ready Date: Wed, 9 Dec 2015 14:21:03 +0100 Message-Id: <1449667265-17525-3-git-send-email-pmladek@suse.com> X-Mailer: git-send-email 1.8.5.6 In-Reply-To: <1449667265-17525-1-git-send-email-pmladek@suse.com> References: <1449667265-17525-1-git-send-email-pmladek@suse.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151209_052155_052518_4458446B X-CRM114-Status: GOOD ( 12.44 ) X-Spam-Score: -2.6 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-mips@linux-mips.org, Daniel Thompson , Jiri Kosina , linux-cris-kernel@axis.com, linux-s390@vger.kernel.org, Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org, Steven Rostedt , adi-buildroot-devel@lists.sourceforge.net, Ingo Molnar , linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, Russell King , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, Petr Mladek , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP NMIs could happen at any time. This patch makes sure that the safe printk() in NMI will schedule IRQ work only when the related structs are initialized. All pending messages are flushed when the IRQ work is being initialized. Signed-off-by: Petr Mladek --- kernel/printk/nmi.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/kernel/printk/nmi.c b/kernel/printk/nmi.c index 7b5ff81b291f..29a498586465 100644 --- a/kernel/printk/nmi.c +++ b/kernel/printk/nmi.c @@ -38,6 +38,7 @@ * were handled or when IRQs are blocked. */ DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default; +static int printk_nmi_irq_ready; #define NMI_LOG_BUF_LEN (4096 - sizeof(atomic_t) - sizeof(struct irq_work)) @@ -83,8 +84,11 @@ again: goto again; /* Get flushed in a more safe context. */ - if (add) + if (add && printk_nmi_irq_ready) { + /* Make sure that IRQ work is really initialized. */ + smp_rmb(); irq_work_queue(&s->work); + } return add; } @@ -190,6 +194,13 @@ void __init printk_nmi_init(void) init_irq_work(&s->work, __printk_nmi_flush); } + + /* Make sure that IRQ works are initialized before enabling. */ + smp_wmb(); + printk_nmi_irq_ready = 1; + + /* Flush pending messages that did not have scheduled IRQ works. */ + printk_nmi_flush(); } void printk_nmi_enter(void)