Re: [PATCH v2 3/3] virtio-blk: Use ioeventfd_attach in start_ioeventfd

[Hanna Czenczek <hreitz@redhat.com>]

On 09.02.24 15:38, Michael Tokarev wrote:
> 02.02.2024 18:31, Hanna Czenczek :
>> Commit d3f6f294aeadd5f88caf0155e4360808c95b3146 ("virtio-blk: always set
>> ioeventfd during startup") has made virtio_blk_start_ioeventfd() always
>> kick the virtqueue (set the ioeventfd), regardless of whether the BB is
>> drained.  That is no longer necessary, because attaching the host
>> notifier will now set the ioeventfd, too; this happens either
>> immediately right here in virtio_blk_start_ioeventfd(), or later when
>> the drain ends, in virtio_blk_ioeventfd_attach().
>>
>> With event_notifier_set() removed, the code becomes the same as the one
>> in virtio_blk_ioeventfd_attach(), so we can reuse that function.
>
> The mentioned comit is v8.2.0-812-gd3f6f294ae, - ie, past 8.2.
> Is this new change still relevant for stable?

Sorry again. :/  This patch is a clean-up patch that won’t apply to 
8.2.  Now, 8.2 does have basically the same logic as described in the 
patch message (d3f6f294aea restored it after it was broken), so a 
similar patch could be made for it (removing the event_notifier_set() 
from virtio_blk_data_plane_start()), but whether we kick the virtqueues 
once or twice on start-up probably won’t make a difference, certainly 
not in terms of correctness.

Hanna