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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1t12XA-00000007own-38uM; Wed, 16 Oct 2024 11:49:44 +0000 Date: Wed, 16 Oct 2024 12:49:44 +0100 From: Matthew Wilcox To: lizhe.67@bytedance.com Cc: peterz@infradead.org, mingo@redhat.com, will@kernel.org, longman@redhat.com, boqun.feng@gmail.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC 1/2] rwsem: introduce upgrade_read interface Message-ID: References: <20241016043600.35139-1-lizhe.67@bytedance.com> <20241016043600.35139-2-lizhe.67@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241016043600.35139-2-lizhe.67@bytedance.com> X-Stat-Signature: zpks7918t4uyf1soqgqh5t3qe7etish3 X-Rspamd-Queue-Id: 433E4140005 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1729079386-470112 X-HE-Meta: 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 sFqYrtjU yLv2bb6Qk+Lpz7tnLLhFW4b6XkhBZy+H+LfvEOB7KBQqHtB1vtISer8sJkntDQ1yi6HZcFeyk/xH1bikmJdgkG8vSzAmXknAmL5KmPCqk7IE26B0bUOa1fuVPRR8DpTNW6YTZ8+VrkKSY3Kx030CYZmZN/qTZENNVLBdcdOFSrXkv4TFF4aZABhDHvMhekrmvrm9GTMpknk75Yq2c+G5fIXz/C0pKin9udxJxISZWr2z4R3AJpR0FpNrc/9Z54Q0ZvjMbmT5tuzTGbIoi59dWW5mXRRepDuZuvMlQpLckw2+kU9dah9W5nHGib+WpsZ9LP5jRw+b6aWa5kMSBA2Nxx4k15/buPxndSZP3QrHwYwzLjXFDUCOYkfMZ8A== 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: List-Subscribe: List-Unsubscribe: On Wed, Oct 16, 2024 at 12:35:59PM +0800, lizhe.67@bytedance.com wrote: > +++ b/include/linux/rwsem.h > @@ -249,6 +249,7 @@ DEFINE_GUARD_COND(rwsem_write, _try, down_write_trylock(_T)) > * downgrade write lock to read lock > */ > extern void downgrade_write(struct rw_semaphore *sem); > +extern int upgrade_read(struct rw_semaphore *sem); This needs __must_check, and I think this should be a bool, not an errno return.