From: Jens Axboe <axboe@kernel.dk>
To: Keith Busch <kbusch@kernel.org>
Cc: io-uring@vger.kernel.org, asml.silence@gmail.com,
naup96721@gmail.com, stable@vger.kernel.org
Subject: Re: [PATCH 1/2] io_uring: ensure ctx->rings is stable for task work flags manipulation
Date: Wed, 11 Mar 2026 09:12:56 -0600 [thread overview]
Message-ID: <002add9f-6cde-4263-92b5-dd74f04f8b10@kernel.dk> (raw)
In-Reply-To: <abGE_CLo4vW_-Tkh@kbusch-mbp>
On 3/11/26 9:06 AM, Keith Busch wrote:
> On Wed, Mar 11, 2026 at 07:11:55AM -0600, Jens Axboe wrote:
>> +/*
>> + * Sets IORING_SQ_TASKRUN in the sq_flags shared with userspace, using the
>> + * RCU protected rings pointer to be safe against concurrent ring resizing.
>> + * Must be called inside an RCU read-side critical section.
>
> You can make the rcu requirement explicit in the code with:
>
> ASSERT(rcu_read_lock_held());
>
> And debug kernels will catch misuse, too.
We have lockdep_assert_in_rcu_read_lock(), that should do it. Did ponder
that, and then I could also kill the comment as it's self documenting
by that point.
--
Jens Axboe
next prev parent reply other threads:[~2026-03-11 15:12 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-11 13:11 [PATCHSET v2] Fix DEFER_TASKRUN ring resize flag manipulation Jens Axboe
2026-03-11 13:11 ` [PATCH 1/2] io_uring: ensure ctx->rings is stable for task work flags manipulation Jens Axboe
2026-03-11 15:06 ` Keith Busch
2026-03-11 15:12 ` Jens Axboe [this message]
2026-03-11 13:11 ` [PATCH 2/2] io_uring/eventfd: use ctx->rings_rcu for flags checking Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2026-03-10 14:45 [PATCHSET 0/2] Fix DEFER_TASKRUN ring resize flag manipulation Jens Axboe
2026-03-10 14:45 ` [PATCH 1/2] io_uring: ensure ctx->rings is stable for task work flags manipulation Jens Axboe
2026-03-11 11:13 ` Pavel Begunkov
2026-03-11 13:05 ` Jens Axboe
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