From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guilherme G. Piccoli Date: Wed, 27 Apr 2022 19:48:58 -0300 Subject: [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path In-Reply-To: <20220427224924.592546-1-gpiccoli@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> Message-ID: <20220427224924.592546-5-gpiccoli@igalia.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kexec@lists.infradead.org Currently the gsmi driver registers a panic notifier as well as reboot and die notifiers. The callbacks registered are called in atomic and very limited context - for instance, panic disables preemption, local IRQs and all other CPUs that aren't running the current panic function. With that said, taking a spinlock in this scenario is a dangerous invitation for a deadlock scenario. So, we fix that in this commit by changing the regular spinlock with a trylock, which is a safer approach. Fixes: 74c5b31c6618 ("driver: Google EFI SMI") Cc: Ard Biesheuvel Cc: David Gow Cc: Evan Green Cc: Julius Werner Signed-off-by: Guilherme G. Piccoli --- drivers/firmware/google/gsmi.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c index adaa492c3d2d..b01ed02e4a87 100644 --- a/drivers/firmware/google/gsmi.c +++ b/drivers/firmware/google/gsmi.c @@ -629,7 +629,10 @@ static int gsmi_shutdown_reason(int reason) if (saved_reason & (1 << reason)) return 0; - spin_lock_irqsave(&gsmi_dev.lock, flags); + if (!spin_trylock_irqsave(&gsmi_dev.lock, flags)) { + rc = -EBUSY; + goto out; + } saved_reason |= (1 << reason); @@ -646,6 +649,7 @@ static int gsmi_shutdown_reason(int reason) spin_unlock_irqrestore(&gsmi_dev.lock, flags); +out: if (rc < 0) printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n"); else -- 2.36.0 From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Guilherme G. Piccoli" Subject: [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path Date: Wed, 27 Apr 2022 19:48:58 -0300 Message-ID: <20220427224924.592546-5-gpiccoli@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=6uCmJtZx2tt75N7rOkxcF9GqtQGKdOCOB58J9Fug6qk=; b=DsA3q7/djrGRVf zMXteEWV417X/UFAJcU0zubjAELfsjiSkE6klaxcNuZM0MAr8EaxEeRPQ6ntJxpVx9IedwBOfsdla wOdlClSqR1hNxBv0barkIhUE5xxRZRiLZyCeMedBcA5QNM++YvS3YtdoWRRShBZHvjB6vs4QDL+a6 U7XfEXzvq9+6sWyti5j+v/i9Nc8gnQsXflFUmfBQHf6O9hoIjym5nfOqtAfY+efaruhEV236BiFby CY29cQOztkw2y5yLYBpvJzgT6o1nOHkgvoAwhx5bDwKfPssL36JKLA2jfa/3qIfreptzzHbtpGElm LcGAafD3wEohbFmE8JAA==; 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=s8xeHJYGrg2PKjTPKivxQn37LuEP6tnBzN9Ru5ARxEw=; b=itLofTxVD3jMCMG1QHrJKsVczn vbwUlm+NWg0pMSOCtSjWETMXDXA/dO9ti0V72q001TMmb2gIzR2yZduw7qvMkCQ0akMjJfPi2/PQc iUqIhedKtPpwa0f3Qs25a8tdm2oshD1/KMZCL+mdxqH7vtpZXZFld+eSj+8owBfmLjMNmktzOqSfY dTb/ic9+j716feaFlMGDFCnVL8lNNI9bMH1gzqsKPsNg72iLmPQmwnJD7EfxHW7NQoAv8T+6Y8VEH 2ohazyjoc9Z+MNXm7Lr7Bh3GLxJ6zmDCTC3SRdi9P8jirAP5MyZi4cLioUm7IG4Ag3/IwiKZ9+K4K 3P27PVmg==; In-Reply-To: <20220427224924.592546-1-gpiccoli@igalia.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+glud-user-mode-linux-devel=m.gmane-mx.org@lists.infradead.org To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, coresight@lists.linaro.org, linuxppc-dev@lists.ozlabs.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-leds@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-pm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-tegra@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, netdev@vger.kernel.org, openipmi-developer@lists.sourceforge.net, rcu@vger.kernel.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, kernel-dev@igalia.com, gpiccoli@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. Currently the gsmi driver registers a panic notifier as well as reboot and die notifiers. The callbacks registered are called in atomic and very limited context - for instance, panic disables preemption, local IRQs and all other CPUs that aren't running the current panic function. With that said, taking a spinlock in this scenario is a dangerous invitation for a deadlock scenario. So, we fix that in this commit by changing the regular spinlock with a trylock, which is a safer approach. Fixes: 74c5b31c6618 ("driver: Google EFI SMI") Cc: Ard Biesheuvel Cc: David Gow Cc: Evan Green Cc: Julius Werner Signed-off-by: Guilherme G. Piccoli --- drivers/firmware/google/gsmi.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c index adaa492c3d2d..b01ed02e4a87 100644 --- a/drivers/firmware/google/gsmi.c +++ b/drivers/firmware/google/gsmi.c @@ -629,7 +629,10 @@ static int gsmi_shutdown_reason(int reason) if (saved_reason & (1 << reason)) return 0; - spin_lock_irqsave(&gsmi_dev.lock, flags); + if (!spin_trylock_irqsave(&gsmi_dev.lock, flags)) { + rc = -EBUSY; + goto out; + } saved_reason |= (1 << reason); @@ -646,6 +649,7 @@ static int gsmi_shutdown_reason(int reason) spin_unlock_irqrestore(&gsmi_dev.lock, flags); +out: if (rc < 0) printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n"); else -- 2.36.0 From mboxrd@z Thu Jan 1 00:00:00 1970 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 E2920C41535 for ; Wed, 27 Apr 2022 22:51:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238874AbiD0Wym (ORCPT ); Wed, 27 Apr 2022 18:54:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35752 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238414AbiD0Wyf (ORCPT ); Wed, 27 Apr 2022 18:54:35 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA47D8CCD3; Wed, 27 Apr 2022 15:51:00 -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=s8xeHJYGrg2PKjTPKivxQn37LuEP6tnBzN9Ru5ARxEw=; b=itLofTxVD3jMCMG1QHrJKsVczn vbwUlm+NWg0pMSOCtSjWETMXDXA/dO9ti0V72q001TMmb2gIzR2yZduw7qvMkCQ0akMjJfPi2/PQc iUqIhedKtPpwa0f3Qs25a8tdm2oshD1/KMZCL+mdxqH7vtpZXZFld+eSj+8owBfmLjMNmktzOqSfY dTb/ic9+j716feaFlMGDFCnVL8lNNI9bMH1gzqsKPsNg72iLmPQmwnJD7EfxHW7NQoAv8T+6Y8VEH 2ohazyjoc9Z+MNXm7Lr7Bh3GLxJ6zmDCTC3SRdi9P8jirAP5MyZi4cLioUm7IG4Ag3/IwiKZ9+K4K 3P27PVmg==; Received: from [179.113.53.197] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1njqUi-00020p-0e; Thu, 28 Apr 2022 00:50:49 +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, bcm-kernel-feedback-list@broadcom.com, coresight@lists.linaro.org, linuxppc-dev@lists.ozlabs.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-leds@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-pm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-tegra@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, netdev@vger.kernel.org, openipmi-developer@lists.sourceforge.net, rcu@vger.kernel.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, kernel-dev@igalia.com, gpiccoli@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, Ard Biesheuvel , David Gow , Evan Green , Julius Werner Subject: [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path Date: Wed, 27 Apr 2022 19:48:58 -0300 Message-Id: <20220427224924.592546-5-gpiccoli@igalia.com> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220427224924.592546-1-gpiccoli@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org Currently the gsmi driver registers a panic notifier as well as reboot and die notifiers. The callbacks registered are called in atomic and very limited context - for instance, panic disables preemption, local IRQs and all other CPUs that aren't running the current panic function. With that said, taking a spinlock in this scenario is a dangerous invitation for a deadlock scenario. So, we fix that in this commit by changing the regular spinlock with a trylock, which is a safer approach. Fixes: 74c5b31c6618 ("driver: Google EFI SMI") Cc: Ard Biesheuvel Cc: David Gow Cc: Evan Green Cc: Julius Werner Signed-off-by: Guilherme G. Piccoli --- drivers/firmware/google/gsmi.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c index adaa492c3d2d..b01ed02e4a87 100644 --- a/drivers/firmware/google/gsmi.c +++ b/drivers/firmware/google/gsmi.c @@ -629,7 +629,10 @@ static int gsmi_shutdown_reason(int reason) if (saved_reason & (1 << reason)) return 0; - spin_lock_irqsave(&gsmi_dev.lock, flags); + if (!spin_trylock_irqsave(&gsmi_dev.lock, flags)) { + rc = -EBUSY; + goto out; + } saved_reason |= (1 << reason); @@ -646,6 +649,7 @@ static int gsmi_shutdown_reason(int reason) spin_unlock_irqrestore(&gsmi_dev.lock, flags); +out: if (rc < 0) printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n"); else -- 2.36.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: "Guilherme G. Piccoli" Subject: [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path Date: Wed, 27 Apr 2022 19:48:58 -0300 Message-Id: <20220427224924.592546-5-gpiccoli@igalia.com> In-Reply-To: <20220427224924.592546-1-gpiccoli@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, coresight@lists.linaro.org, linuxppc-dev@lists.ozlabs.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-leds@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-pm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-tegra@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, netdev@vger.kernel.org, openipmi-developer@lists.sourceforge.net, rcu@vger.kernel.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, kernel-dev@igalia.com, gpiccoli@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, Ard Biesheuvel , David Gow , Evan Green , Julius Werner Currently the gsmi driver registers a panic notifier as well as reboot and die notifiers. The callbacks registered are called in atomic and very limited context - for instance, panic disables preemption, local IRQs and all other CPUs that aren't running the current panic function. With that said, taking a spinlock in this scenario is a dangerous invitation for a deadlock scenario. So, we fix that in this commit by changing the regular spinlock with a trylock, which is a safer approach. Fixes: 74c5b31c6618 ("driver: Google EFI SMI") Cc: Ard Biesheuvel Cc: David Gow Cc: Evan Green Cc: Julius Werner Signed-off-by: Guilherme G. Piccoli --- drivers/firmware/google/gsmi.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c index adaa492c3d2d..b01ed02e4a87 100644 --- a/drivers/firmware/google/gsmi.c +++ b/drivers/firmware/google/gsmi.c @@ -629,7 +629,10 @@ static int gsmi_shutdown_reason(int reason) if (saved_reason & (1 << reason)) return 0; - spin_lock_irqsave(&gsmi_dev.lock, flags); + if (!spin_trylock_irqsave(&gsmi_dev.lock, flags)) { + rc = -EBUSY; + goto out; + } saved_reason |= (1 << reason); @@ -646,6 +649,7 @@ static int gsmi_shutdown_reason(int reason) spin_unlock_irqrestore(&gsmi_dev.lock, flags); +out: if (rc < 0) printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n"); else -- 2.36.0 _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um From mboxrd@z Thu Jan 1 00:00:00 1970 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 734F1C433EF for ; Thu, 28 Apr 2022 01:50:36 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Kpdqb0KJhz3fqc for ; Thu, 28 Apr 2022 11:50:35 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=igalia.com header.i=@igalia.com header.a=rsa-sha256 header.s=20170329 header.b=itLofTxV; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=igalia.com (client-ip=178.60.130.6; helo=fanzine2.igalia.com; envelope-from=gpiccoli@igalia.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=igalia.com header.i=@igalia.com header.a=rsa-sha256 header.s=20170329 header.b=itLofTxV; dkim-atps=neutral Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KpZZx6PB1z3bcY for ; Thu, 28 Apr 2022 09:24:25 +1000 (AEST) 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=s8xeHJYGrg2PKjTPKivxQn37LuEP6tnBzN9Ru5ARxEw=; b=itLofTxVD3jMCMG1QHrJKsVczn vbwUlm+NWg0pMSOCtSjWETMXDXA/dO9ti0V72q001TMmb2gIzR2yZduw7qvMkCQ0akMjJfPi2/PQc iUqIhedKtPpwa0f3Qs25a8tdm2oshD1/KMZCL+mdxqH7vtpZXZFld+eSj+8owBfmLjMNmktzOqSfY dTb/ic9+j716feaFlMGDFCnVL8lNNI9bMH1gzqsKPsNg72iLmPQmwnJD7EfxHW7NQoAv8T+6Y8VEH 2ohazyjoc9Z+MNXm7Lr7Bh3GLxJ6zmDCTC3SRdi9P8jirAP5MyZi4cLioUm7IG4Ag3/IwiKZ9+K4K 3P27PVmg==; Received: from [179.113.53.197] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1njqUi-00020p-0e; Thu, 28 Apr 2022 00:50:49 +0200 From: "Guilherme G. Piccoli" To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Subject: [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path Date: Wed, 27 Apr 2022 19:48:58 -0300 Message-Id: <20220427224924.592546-5-gpiccoli@igalia.com> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220427224924.592546-1-gpiccoli@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Thu, 28 Apr 2022 11:34:03 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-hyperv@vger.kernel.org, halves@canonical.com, David Gow , gregkh@linuxfoundation.org, peterz@infradead.org, alejandro.j.jimenez@oracle.com, linux-remoteproc@vger.kernel.org, feng.tang@intel.com, linux-mips@vger.kernel.org, hidehiro.kawai.ez@hitachi.com, sparclinux@vger.kernel.org, will@kernel.org, tglx@linutronix.de, linux-leds@vger.kernel.org, linux-s390@vger.kernel.org, mikelley@microsoft.com, john.ogness@linutronix.de, corbet@lwn.net, paulmck@kernel.org, fabiomirmar@gmail.com, x86@kernel.org, Evan Green , Ard Biesheuvel , mingo@redhat.com, bcm-kernel-feedback-list@broadcom.com, xen-devel@lists.xenproject.org, dyoung@redhat.com, vgoyal@redhat.com, linux-xtensa@linux-xtensa.org, dave.hansen@linux.intel.com, keescook@chromium.org, arnd@arndb.de, linux-pm@vger.kernel.org, coresight@lists.linaro.org, linux-um@lists.infradead.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, luto@kernel.org, linux-tegra@vger.kernel.org, openipmi-developer@lists.sourceforge.net, andriy.shevchenko@linux.intel.com, senozhatsky@chromium.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, jgross@suse.com, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, kernel@gpiccoli.net, linux-kernel@vger.kernel.org, stern@rowland.harvard.edu, gpiccoli@igalia.com, d.hatayama@jp.fujitsu.com, mhiramat@kernel.org, kernel-dev@igalia.com, linux-alpha@vger.kernel.org, Julius Werner , vkuznets@redhat.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Currently the gsmi driver registers a panic notifier as well as reboot and die notifiers. The callbacks registered are called in atomic and very limited context - for instance, panic disables preemption, local IRQs and all other CPUs that aren't running the current panic function. With that said, taking a spinlock in this scenario is a dangerous invitation for a deadlock scenario. So, we fix that in this commit by changing the regular spinlock with a trylock, which is a safer approach. Fixes: 74c5b31c6618 ("driver: Google EFI SMI") Cc: Ard Biesheuvel Cc: David Gow Cc: Evan Green Cc: Julius Werner Signed-off-by: Guilherme G. Piccoli --- drivers/firmware/google/gsmi.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c index adaa492c3d2d..b01ed02e4a87 100644 --- a/drivers/firmware/google/gsmi.c +++ b/drivers/firmware/google/gsmi.c @@ -629,7 +629,10 @@ static int gsmi_shutdown_reason(int reason) if (saved_reason & (1 << reason)) return 0; - spin_lock_irqsave(&gsmi_dev.lock, flags); + if (!spin_trylock_irqsave(&gsmi_dev.lock, flags)) { + rc = -EBUSY; + goto out; + } saved_reason |= (1 << reason); @@ -646,6 +649,7 @@ static int gsmi_shutdown_reason(int reason) spin_unlock_irqrestore(&gsmi_dev.lock, flags); +out: if (rc < 0) printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n"); else -- 2.36.0