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Date:   Fri, 23 Jul 2021 00:10:32 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 3/3] io_uring: refactor io_sq_offload_create()
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On Thu, Jul 22, 2021 at 05:42:55PM -0600, Jens Axboe wrote:

> > So how can we possibly get there with tsk->files == NULL and what does it
> > have to do with files, anyway?
> 
> It's not the clearest, but the files check is just to distinguish between
> exec vs normal cancel. For exec, we pass in files == NULL. It's not
> related to task->files being NULL or not, we explicitly pass NULL for
> exec.

Er...  So turn that argument into bool cancel_all, and pass false on exit and
true on exit?  While we are at it, what happens if you pass io_uring descriptor
to another process, close yours and then have the recepient close the one it
has gotten?  AFAICS, io_ring_ctx_wait_and_kill(ctx) will be called in context
of a process that has never done anything io_uring-related.  Can it end up
trying to resubmit some requests?

I rather hope it can't happen, but I don't see what would prevent it...