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Wed, 11 Mar 2026 08:12:58 -0700 (PDT) Received: from [192.168.1.150] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-4177e6c7885sm2267891fac.17.2026.03.11.08.12.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Mar 2026 08:12:57 -0700 (PDT) Message-ID: <002add9f-6cde-4263-92b5-dd74f04f8b10@kernel.dk> Date: Wed, 11 Mar 2026 09:12:56 -0600 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] io_uring: ensure ctx->rings is stable for task work flags manipulation To: Keith Busch Cc: io-uring@vger.kernel.org, asml.silence@gmail.com, naup96721@gmail.com, stable@vger.kernel.org References: <20260311131336.197028-1-axboe@kernel.dk> <20260311131336.197028-2-axboe@kernel.dk> Content-Language: en-US From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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