[PATCH] nvme-pci: silence a lockdep complaint

[Keith Busch]

On Wed, May 22, 2024 at 12:18:57PM +0000, Shinichiro Kawasaki wrote:
> On May 22, 2024 / 12:15, Sagi Grimberg wrote:
> > lockdep complains about the timeout handler running concurrently with
> > the reset work which is syncing the IO request queues (which in turn
> > flushes the timeout work).
> > 
> > We know it cannot be the case because the ctrl state machine prevents
> > the timeout handler from disabling the ctrl when the reset work is
> > running (changing ctrl state to RESETTING will fail, and the state is not
> > terminal). If this assumption happens to break in the future, we won't
> > have lockdep to assist, but for the time being we are simply seeing
> > false-positive complaints from it...
> > 
> > Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki at wdc.com>
> > Suggested-by: Keith Busch <kbusch at kernel.org>
> > Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
> 
> Sagi, thank you very much. I confirmed this patch avoids the lockdep WARN
> observed with the blktests test case nvme/050 [1]. When I repeated the test case
> around 10 times on v6.9 kernel without this patch, the lockdep WARN was
> recreated in stable manner. After applying this patch, the WARN was not
> observed even when the test case is repeated 100 times.
> 
> Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki at wdc.com>

This is not desireable, but I give up trying to appease lockdep for this
one.