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Tue, 6 Jan 2026 18:41:23 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 0+HZM1NXXWmDWQAAD6G6ig (envelope-from ); Tue, 06 Jan 2026 18:41:23 +0000 From: Gabriel Krisman Bertazi To: Caleb Sander Mateos Cc: Jens Axboe , Joanne Koong , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 0/3] io_uring: use release-acquire ordering for IORING_SETUP_R_DISABLED In-Reply-To: <20260105210543.3471082-1-csander@purestorage.com> (Caleb Sander Mateos's message of "Mon, 5 Jan 2026 14:05:39 -0700") References: <20260105210543.3471082-1-csander@purestorage.com> Date: Tue, 06 Jan 2026 13:41:22 -0500 Message-ID: <875x9e7fe5.fsf@mailhost.krisman.be> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Flag: NO X-Spam-Score: -4.29 X-Spam-Level: X-Spamd-Result: default: False [-4.29 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.19)[-0.971]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[kernel.dk,gmail.com,vger.kernel.org]; RCPT_COUNT_FIVE(0.00)[5]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,purestorage.com:email] Caleb Sander Mateos writes: > io_uring_enter(), __io_msg_ring_data(), and io_msg_send_fd() read > ctx->flags and ctx->submitter_task without holding the ctx's uring_lock. > This means they may race with the assignment to ctx->submitter_task and > the clearing of IORING_SETUP_R_DISABLED from ctx->flags in > io_register_enable_rings(). Ensure the correct ordering of the > ctx->flags and ctx->submitter_task memory accesses by storing to > ctx->flags using release ordering and loading it using acquire ordering. > > Using release-acquire ordering for IORING_SETUP_R_DISABLED ensures the > assignment to ctx->submitter_task in io_register_enable_rings() can't > race with msg_ring's accesses, so drop the unneeded {READ,WRITE}_ONCE() > and the NULL checks. Hi Caleb, This looks good, I don't have any comments. Feel free to add: Reviewed-by: Gabriel Krisman Bertazi Thanks, -- Gabriel Krisman Bertazi