Re: [PATCH] sbitmap: Use single per-bitmap counting to wake up queued tags

Jens Axboe
2022-11-11T15:38:58Z

On Sat, 5 Nov 2022 19:10:55 -0400, Gabriel Krisman Bertazi wrote:
> sbitmap suffers from code complexity, as demonstrated by recent fixes,
> and eventual lost wake ups on nested I/O completion. The later happens,
> from what I understand, due to the non-atomic nature of the updates to
> wait_cnt, which needs to be subtracted and eventually reset when equal
> to zero. This two step process can eventually miss an update when a
> nested completion happens to interrupt the CPU in between the wait_cnt
> updates. This is very hard to fix, as shown by the recent changes to
> this code.
>
> [...]

Applied, thanks!

[1/1] sbitmap: Use single per-bitmap counting to wake up queued tags
commit: 4f8126bb2308066b877859e4b5923ffb54143630

Best regards,
--
Jens Axboe