ACK/Cmnt: [SRU][F/J:linux-bluefield][PATCH v1 0/1] UBUNTU: SAUCE: mlxbf-gige: Fix kernel panic at shutdown

[Tim Gardner]

On 6/2/23 11:04 AM, Asmaa Mnebhi wrote:
> BugLink: https://bugs.launchpad.net/bugs/2022370
> 
> SRU Justification:
> 
> [Impact]
> 
> We occasionally see a race condition (once every 350 reboots) where napi is still
> running (mlxbf_gige_poll) while a shutdown has been initiated through "reboot".
> Since mlxbf_gige_poll is still running, it tries to access a NULL pointer and as
> a result causes a kernel panic.
> 
> [Fix]
> 
> The fix is to explicitly disable napi and dequeue it during shutdown.
> mlxbf_gige_remove already calls:
> unregister_netdev->unregister_netdevice->unregister_netdev_queue->
> rollback_registered->rollback_registered_many->dev_close_many->
> __dev_close_many->ndo_stop->mlxbf_gige_stop which stops napi
> 
> So use mlxbf_gige_remove in place of the existing shutdown logic.
> 
> [Test Case]
> 
> * Issue at least 1000 reboots from linux and make sure there is no panic caused by the mlxbf-gige driver.
> 
> [Regression Potential]
> 
> * since this issue is hard to reproduce, it hasn't been tested thoroughly yet. so it needs several reboot loops to validate it.
> 
Acked-by: Tim Gardner <tim.gardner at canonical.com>

ACK based on Bart's analysis.
-- 
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Tim Gardner
Canonical, Inc