On 21:02-20230509, Benjamin Bara wrote:
> From: Benjamin Bara <benjamin.bara@xxxxxxxxxxx>
>
> As the emergency restart does not call kernel_restart_prepare(), the
> system_state stays in SYSTEM_RUNNING.
>
> Since bae1d3a05a8b, this hinders i2c_in_atomic_xfer_mode() from becoming
> active, and therefore might lead to avoidable warnings in the restart
> handlers, e.g.:
>
> [ 12.667612] WARNING: CPU: 1 PID: 1 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x33c/0x6b0
> [ 12.676926] Voluntary context switch within RCU read-side critical section!
> ...
> [ 12.742376] schedule_timeout from wait_for_completion_timeout+0x90/0x114
> [ 12.749179] wait_for_completion_timeout from tegra_i2c_wait_completion+0x40/0x70
> ...
> [ 12.994527] atomic_notifier_call_chain from machine_restart+0x34/0x58
> [ 13.001050] machine_restart from panic+0x2a8/0x32c
>
> Avoid these by setting the correct system_state.
>
> Fixes: bae1d3a05a8b ("i2c: core: remove use of in_atomic()")
> Cc: stable@xxxxxxxxxxxxxxx # v5.2+
> Signed-off-by: Benjamin Bara <benjamin.bara@xxxxxxxxxxx>
> ---
> kernel/reboot.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/reboot.c b/kernel/reboot.c
> index 3bba88c7ffc6..6ebef11c8876 100644
> --- a/kernel/reboot.c
> +++ b/kernel/reboot.c
> @@ -74,6 +74,7 @@ void __weak (*pm_power_off)(void);
> void emergency_restart(void)
> {
> kmsg_dump(KMSG_DUMP_EMERG);
> + system_state = SYSTEM_RESTART;
> machine_emergency_restart();
> }
> EXPORT_SYMBOL_GPL(emergency_restart);
>
> --
> 2.34.1
>
Tested-by: Nishanth Menon <nm@xxxxxx>
This in addition to a deeper bug in our driver seems to have helped
resolve a report we had been looking at. Tested on beagleplay platform
https://lore.kernel.org/all/ZGeHMjlnob2GFyHF@xxxxxxxxxxxxxxxxxxxxxxxxxxxx/
--
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3 1A34 DDB5 849D 1736 249D
