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Goncalves" , Andrew Morton , Boqun Feng , Ingo Molnar , John Ogness , Mel Gorman , Michal Hocko , Peter Zijlstra , Petr Mladek , Thomas Gleixner , Waiman Long , Will Deacon Subject: Re: [PATCH v2 1/2] seqlock: Do the lockdep annotation before locking in do_write_seqcount_begin_nested() Message-ID: <20230626081254.XmorFrhs@linutronix.de> References: <20230623171232.892937-1-bigeasy@linutronix.de> <20230623171232.892937-2-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: X-Rspamd-Queue-Id: D318E100007 X-Rspam-User: X-Stat-Signature: riqag8h4j6dkrj8heoahsy6u5yut4wrh X-Rspamd-Server: rspam01 X-HE-Tag: 1687767178-631984 X-HE-Meta: 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 NEg54Dg1 BXx5o21iY5wo3A5Pu6ASLlpW95z1g1uLWcww3NOo1/XSBNoLUTvnlD7k0UuUT4E7vCOc4nea/BBrFRuOvytRmS0rA7lSZ2IWCNUHYNX3vmD8NW9USSYoMVsnAE45RB+Q6W+4iI1XJ+cl/+ujKeqRDqqCZ/U1JnIhal+Rph5RC0sW1EMc6Hei+JfW1lJDuaRUZjPd3EWVeBzB33zOI45+VWgkQFQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023-06-24 15:54:12 [+0900], Tetsuo Handa wrote: > Why not to do the same on the end side? >=20 > static inline void do_write_seqcount_end(seqcount_t *s) > { > - seqcount_release(&s->dep_map, _RET_IP_); > do_raw_write_seqcount_end(s); > + seqcount_release(&s->dep_map, _RET_IP_); > } I don't have a compelling argument for doing it. It is probably better to release the lock from lockdep's point of view and then really release it (so it can't be acquired before it is released). Looking at other locking primitives (spin_lock_unlock(), mutex_unlock(),=E2=80=A6) that is what they do in the unlock path: lockdep annotation followed by the actual operation. Therefore I would keep the current ordering to remain in-sync with the other primitives. Sebastian