Re: [PATCH] percpu-refcount: relax limit on percpu_ref_reinit()

Bart Van Assche
2018-09-09T23:37:24Z

On Sun, 2018-09-09 at 20:58 +0800, Ming Lei wrote:
> Now percpu_ref_reinit() can only be done on one percpu refcounter
> when it drops zero. And the limit shouldn't be so strict, and it
> is quite straightforward that percpu_ref_reinit() can be done when
> this counter is at atomic mode.
>
> This patch relaxes the limit, so we may avoid extra change[1] for NVMe
> timeout's requirement.
>
> [1] https://marc.info/?l=linux-kernel&m=153612052611020&w=2

Is the NVMe driver the only block driver that hangs if it is attempted to
freeze its request queue when a request times out? If so, can this hang be
fixed by modifying the NVMe driver instead of by modifying the percpu
refcount implementation?

Thanks,

Bart.