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Mon, 20 Oct 2025 15:00:02 +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 hSzAKHJO9miNQQAAD6G6ig (envelope-from ); Mon, 20 Oct 2025 15:00:02 +0000 From: Gabriel Krisman Bertazi To: Alok Tiwari Cc: csander@purestorage.com, axboe@kernel.dk, io-uring@vger.kernel.org, alok.a.tiwarilinux@gmail.com Subject: Re: [PATCH v2] io_uring: fix incorrect unlikely() usage in io_waitid_prep() In-Reply-To: <20251018193300.1517312-1-alok.a.tiwari@oracle.com> (Alok Tiwari's message of "Sat, 18 Oct 2025 12:32:54 -0700") References: <20251018193300.1517312-1-alok.a.tiwari@oracle.com> Date: Mon, 20 Oct 2025 11:00:01 -0400 Message-ID: <87h5vt39fy.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-Rspamd-Queue-Id: 2F32F1F38D X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[99.99%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; FREEMAIL_CC(0.00)[purestorage.com,kernel.dk,vger.kernel.org,gmail.com]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[oracle.com:email,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:email,suse.de:dkim] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -3.01 X-Spam-Level: Alok Tiwari writes: > The negation operator incorrectly places outside the unlikely() macro: > > if (!unlikely(iwa)) > > This inverted the compiler branch prediction hint, marking the NULL > case as likely instead of unlikely. The intent is to indicate that > allocation failures are rare, consistent with common kernel patterns. > > Moving the negation inside unlikely(): > > if (unlikely(!iwa)) > > Fixes: 2b4fc4cd43f2 ("io_uring/waitid: setup async data in the prep handler") > Signed-off-by: Alok Tiwari Reviewed-by: Gabriel Krisman Bertazi -- Gabriel Krisman Bertazi