From: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
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,
"Guilherme G. Piccoli" <gpiccoli@igalia.com>,
linux-efi@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
David Gow <davidgow@google.com>,
Evan Green <evgreen@chromium.org>,
Julius Werner <jwerner@chromium.org>
Subject: [PATCH v2 03/13] firmware: google: Test spinlock on panic path to avoid lockups
Date: Tue, 19 Jul 2022 16:53:16 -0300 [thread overview]
Message-ID: <20220719195325.402745-4-gpiccoli@igalia.com> (raw)
In-Reply-To: <20220719195325.402745-1-gpiccoli@igalia.com>
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 and local IRQs, also all secondary CPUs (not executing
the panic path) are shutdown.
With that said, taking a spinlock in this scenario is a dangerous
invitation for lockup scenarios. So, fix that by checking if the
spinlock is free to acquire in the panic notifier callback - if not,
bail-out and avoid a potential hang.
Fixes: 74c5b31c6618 ("driver: Google EFI SMI")
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: David Gow <davidgow@google.com>
Cc: Evan Green <evgreen@chromium.org>
Cc: Julius Werner <jwerner@chromium.org>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
---
V2:
- do not use spin_trylock anymore, to avoid messing with
non-panic paths; now we just check the spinlock state in
the panic notifier before taking it. Thanks Evan for the
review/idea!
drivers/firmware/google/gsmi.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c
index adaa492c3d2d..3ef5f3c0b4e4 100644
--- a/drivers/firmware/google/gsmi.c
+++ b/drivers/firmware/google/gsmi.c
@@ -681,6 +681,14 @@ static struct notifier_block gsmi_die_notifier = {
static int gsmi_panic_callback(struct notifier_block *nb,
unsigned long reason, void *arg)
{
+ /*
+ * Perform the lock check before effectively trying
+ * to acquire it on gsmi_shutdown_reason() to avoid
+ * potential lockups in atomic context.
+ */
+ if (spin_is_locked(&gsmi_dev.lock))
+ return NOTIFY_DONE;
+
gsmi_shutdown_reason(GSMI_SHUTDOWN_PANIC);
return NOTIFY_DONE;
}
--
2.37.1
next prev parent reply other threads:[~2022-07-19 19:55 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-19 19:53 [PATCH v2 00/13] The panic notifiers refactor strikes back - fixes/clean-ups Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 01/13] ARM: Disable FIQs (but not IRQs) on CPUs shutdown paths Guilherme G. Piccoli
2022-08-07 15:35 ` Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 02/13] notifier: Add panic notifiers info and purge trailing whitespaces Guilherme G. Piccoli
2022-08-03 9:21 ` Baoquan He
2022-07-19 19:53 ` Guilherme G. Piccoli [this message]
2022-08-07 15:38 ` [PATCH v2 03/13] firmware: google: Test spinlock on panic path to avoid lockups Guilherme G. Piccoli
2022-08-08 5:07 ` Evan Green
2022-08-08 15:14 ` Guilherme G. Piccoli
2022-08-08 15:26 ` Greg Kroah-Hartman
2022-08-08 15:37 ` Guilherme G. Piccoli
2022-08-10 12:54 ` Greg Kroah-Hartman
2022-07-19 19:53 ` [PATCH v2 04/13] soc: bcm: brcmstb: Document panic notifier action and remove useless header Guilherme G. Piccoli
2022-07-20 23:00 ` Florian Fainelli
2022-07-21 13:17 ` Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 05/13] alpha: Clean-up the panic notifier code Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 06/13] um: Improve panic notifiers consistency and ordering Guilherme G. Piccoli
2022-08-07 15:40 ` Guilherme G. Piccoli
2022-08-09 18:09 ` Johannes Berg
2022-08-09 19:03 ` Guilherme G. Piccoli
2022-08-09 19:08 ` Johannes Berg
2022-08-09 19:45 ` Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 07/13] parisc: Replace regular spinlock with spin_trylock on panic path Guilherme G. Piccoli
2022-07-20 1:43 ` Jeroen Roovers
2022-07-21 13:19 ` Guilherme G. Piccoli
2022-07-21 13:45 ` Helge Deller
2022-07-21 14:00 ` Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 08/13] tracing: Improve panic/die notifiers Guilherme G. Piccoli
2022-08-03 9:36 ` Baoquan He
2022-08-03 9:52 ` Baoquan He
2022-08-03 11:44 ` Guilherme G. Piccoli
2022-08-07 15:46 ` Guilherme G. Piccoli
2022-08-16 14:14 ` Steven Rostedt
2022-08-16 14:57 ` Alan Stern
2022-08-16 15:52 ` Steven Rostedt
2022-08-16 20:12 ` Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 09/13] notifier: Show function names on notifier routines if DEBUG_NOTIFIERS is set Guilherme G. Piccoli
2022-07-19 20:33 ` Arjan van de Ven
2022-07-19 20:44 ` Guilherme G. Piccoli
2022-07-19 20:48 ` Arjan van de Ven
2022-07-19 21:00 ` Guilherme G. Piccoli
2022-07-19 22:04 ` Arjan van de Ven
2022-07-21 13:20 ` Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 10/13] EDAC/altera: Skip the panic notifier if kdump is loaded Guilherme G. Piccoli
2022-08-07 15:48 ` Guilherme G. Piccoli
2022-08-16 18:44 ` Dinh Nguyen
2022-08-16 20:16 ` Guilherme G. Piccoli
2022-08-17 17:31 ` Borislav Petkov
2022-08-17 18:45 ` Guilherme G. Piccoli
2022-08-17 19:34 ` Borislav Petkov
2022-08-17 20:28 ` Guilherme G. Piccoli
2022-08-17 21:02 ` Borislav Petkov
2022-08-17 21:39 ` Guilherme G. Piccoli
2022-08-17 21:46 ` Borislav Petkov
2022-08-17 21:56 ` Guilherme G. Piccoli
2022-08-17 22:00 ` Borislav Petkov
2022-08-17 22:09 ` Guilherme G. Piccoli
2022-08-17 22:19 ` Borislav Petkov
2022-08-17 22:49 ` Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 11/13] video/hyperv_fb: Avoid taking busy spinlock on panic path Guilherme G. Piccoli
2022-07-25 18:09 ` Michael Kelley (LINUX)
2022-07-25 22:05 ` Guilherme G. Piccoli
2022-07-19 19:53 ` [PATCH v2 12/13] drivers/hv/vmbus, video/hyperv_fb: Untangle and refactor Hyper-V panic notifiers Guilherme G. Piccoli
2022-07-25 18:55 ` Michael Kelley (LINUX)
2022-07-19 19:53 ` [PATCH v2 13/13] panic: Fixes the panic_print NMI backtrace setting Guilherme G. Piccoli
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