Re: [PATCH 3/5] io_uring: add support for getdents

[Jens Axboe <axboe@kernel.dk>]

On 7/31/23 6:47?PM, Matthew Wilcox wrote:
> On Mon, Jul 31, 2023 at 06:28:02PM -0600, Jens Axboe wrote:
>> It's also not an absolute thing, like memory allocations are. It's
>> perfectly fine to grab a mutex under NOWAIT issue. What you should not
>> do is grab a mutex that someone else can grab while waiting on IO. This
>> kind of extra context is only available in the code in question, not
>> generically for eg mutex locking.
> 
> Is that information documented somewhere?  I didn't know that was the
> rule, and I wouldn't be surprised if that's news to several of the other
> people on this thread.

I've mentioned it in various threads, but would probably be good to
write down somewhere if that actually makes more people see it. I'm
dubious, but since it applies to NOWAIT in general, would be a good
thing to do regardless. And then at least I could point to that rather
than have to write up a long description every time.

-- 
Jens Axboe