diff options
| author | Guilherme G. Piccoli <gpiccoli@igalia.com> | 2022-09-09 23:07:55 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-10-04 00:21:42 +0300 |
| commit | 1179083ff07698b870da30a5aad34d44ed5dae10 (patch) | |
| tree | 3eae5963ffac319439e1bc7933277b3d71e1121a /drivers | |
| parent | 5758478a3d3c42a78ee9ddc4b08db3e968a68058 (diff) | |
| download | linux-1179083ff07698b870da30a5aad34d44ed5dae10.tar.xz | |
firmware: google: test spinlock on panic path to avoid lockups
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.
Link: https://lkml.kernel.org/r/20220909200755.189679-1-gpiccoli@igalia.com
Fixes: 74c5b31c6618 ("driver: Google EFI SMI")
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Reviewed-by: Evan Green <evgreen@chromium.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: David Gow <davidgow@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/firmware/google/gsmi.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c index adaa492c3d2d..4e2575dfeb90 100644 --- a/drivers/firmware/google/gsmi.c +++ b/drivers/firmware/google/gsmi.c @@ -681,6 +681,15 @@ static struct notifier_block gsmi_die_notifier = { static int gsmi_panic_callback(struct notifier_block *nb, unsigned long reason, void *arg) { + + /* + * Panic callbacks are executed with all other CPUs stopped, + * so we must not attempt to spin waiting for gsmi_dev.lock + * to be released. + */ + if (spin_is_locked(&gsmi_dev.lock)) + return NOTIFY_DONE; + gsmi_shutdown_reason(GSMI_SHUTDOWN_PANIC); return NOTIFY_DONE; } |