From patchwork Tue Aug 16 15:59:53 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Pieralisi X-Patchwork-Id: 9284191 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5BA2F600CB for ; Tue, 16 Aug 2016 16:01:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 46E12286E2 for ; Tue, 16 Aug 2016 16:01:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3BA36286E7; Tue, 16 Aug 2016 16:01:53 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 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.wl.linuxfoundation.org (Postfix) with ESMTPS id 4F571286E2 for ; Tue, 16 Aug 2016 16:01:52 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bZgn7-0002nZ-Tq; Tue, 16 Aug 2016 16:00:37 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bZgmt-0001WH-0Y for linux-arm-kernel@lists.infradead.org; Tue, 16 Aug 2016 16:00:24 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2B51030C; Tue, 16 Aug 2016 09:01:35 -0700 (PDT) Received: from red-moon.cambridge.arm.com (red-moon.cambridge.arm.com [10.1.206.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0D9283F215; Tue, 16 Aug 2016 09:00:00 -0700 (PDT) From: Lorenzo Pieralisi To: linux-acpi@vger.kernel.org Subject: [PATCH 2/2] drivers: acpi: replace acpi_probe_lock spinlock with mutex Date: Tue, 16 Aug 2016 16:59:53 +0100 Message-Id: <1471363193-16559-2-git-send-email-lorenzo.pieralisi@arm.com> X-Mailer: git-send-email 2.6.4 In-Reply-To: <1471363193-16559-1-git-send-email-lorenzo.pieralisi@arm.com> References: <1471363193-16559-1-git-send-email-lorenzo.pieralisi@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160816_090023_135151_B1230BCD X-CRM114-Status: GOOD ( 10.35 ) 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: Lorenzo Pieralisi , Marc Zyngier , Tomasz Nowicki , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, 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-Virus-Scanned: ClamAV using ClamSMTP Commit e647b532275b ("ACPI: Add early device probing infrastructure") introduced code that allows inserting driver specific struct acpi_probe_entry probe entries into acpi linker sections (one per-subsystem, eg irqchip, clocksource) that are then walked to retrieve the data and function hooks required to probe the respective kernel components. Probing for all entries in a section is triggered through the __acpi_probe_device_table() function, that in turn, according to the table id a given probe entry reports parses the table with the function retrieved from the respective section structures (ie struct acpi_probe_entry). Owing to the current ACPI table parsing implementation, the __acpi_probe_device_table() function has to share global variables with the acpi_match_madt() function, so in order to guarantee mutual exclusion locking is required between the two functions. Current kernel code implements the locking through the acpi_probe_lock spinlock; this has the side effect of requiring all code called within the lock (ie struct acpi_probe_entry.probe_{table/subtbl} hooks) not to sleep. However, kernel subsystems that make use of the early probing infrastructure, are relying on kernel APIs that may sleep (eg irq_domain_alloc_fwnode(), among others) in the function calls pointed at by struct acpi_probe_entry.{probe_table/subtbl} entries (eg gic_v2_acpi_init()), which is a bug. Since __acpi_probe_device_table() is called from context that is allowed to sleep the acpi_probe_lock spinlock can be replaced with a mutex; this fixes the issue whilst still guaranteeing mutual exclusion. Signed-off-by: Lorenzo Pieralisi Fixes: e647b532275b ("ACPI: Add early device probing infrastructure") Cc: Tomasz Nowicki Cc: "Rafael J. Wysocki" Cc: Marc Zyngier --- drivers/acpi/scan.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index ad9fc84..e878fc7 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -2054,7 +2054,7 @@ int __init acpi_scan_init(void) static struct acpi_probe_entry *ape; static int acpi_probe_count; -static DEFINE_SPINLOCK(acpi_probe_lock); +static DEFINE_MUTEX(acpi_probe_mutex); static int __init acpi_match_madt(struct acpi_subtable_header *header, const unsigned long end) @@ -2073,7 +2073,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr) if (acpi_disabled) return 0; - spin_lock(&acpi_probe_lock); + mutex_lock(&acpi_probe_mutex); for (ape = ap_head; nr; ape++, nr--) { if (ACPI_COMPARE_NAME(ACPI_SIG_MADT, ape->id)) { acpi_probe_count = 0; @@ -2086,7 +2086,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr) count++; } } - spin_unlock(&acpi_probe_lock); + mutex_unlock(&acpi_probe_mutex); return count; }