linux-kernel - Re: io_uring: process task work in io_uring

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Message-ID: <CAG48ez1i9pTYihJAd8sXC5BdP+5fLO-mcqDU1TdA2C3bKTXYCw@mail.gmail.com>
Date:   Thu, 8 Oct 2020 21:13:15 +0200
From:   Jann Horn <jannh@...gle.com>
To:     Colin Ian King <colin.king@...onical.com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        io-uring <io-uring@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: io_uring: process task work in io_uring_register()

On Thu, Oct 8, 2020 at 8:24 PM Colin Ian King <colin.king@...onical.com> wrote:
> Static analysis with Coverity has detected a "dead-code" issue with the
> following commit:
>
> commit af9c1a44f8dee7a958e07977f24ba40e3c770987
> Author: Jens Axboe <axboe@...nel.dk>
> Date:   Thu Sep 24 13:32:18 2020 -0600
>
>     io_uring: process task work in io_uring_register()
>
> The analysis is as follows:
>
> 9513                do {
> 9514                        ret =
> wait_for_completion_interruptible(&ctx->ref_comp);
>
> cond_const: Condition ret, taking false branch. Now the value of ret is
> equal to 0.

Does this mean Coverity is claiming that
wait_for_completion_interruptible() can't return non-zero values? If
so, can you figure out why Coverity thinks that? If that was true,
it'd sound like a core kernel bug, rather than a uring issue...