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netdev@vger.kernel.org, matthew.brost@intel.com, her0gyugyu@gmail.com Subject: [PATCH v16 29/42] cpu/hotplug: use a weaker annotation in AP thread Date: Mon, 19 May 2025 18:18:13 +0900 Message-Id: <20250519091826.19752-30-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20250519091826.19752-1-byungchul@sk.com> References: <20250519091826.19752-1-byungchul@sk.com> X-Brightmail-Tracker: H4sIAAAAAAAAAzWSbUxTdxTG/d97e+9tZ+WmEnfBJcxGs8niCwaWs2SaJVv0P+MLiX4w24d5 I3e0ASopiuBc0k5qnJWCOmAqYgFzraWM2mIUtYpFKgVFkIrAeJeoBJCl2CqC2wqbX05+eZ7z POfLYUmVTxbLanX7RL1OSFfTCkoxsbB8VebreM1aS10UhF4dpaC0xkFD2x9VCBy1RgJGGzfB k/A4gpkHD0koKWpDUD7UR0Ktrx+Bx/YLDR0jiyAQmqTBX2Sm4XBlDQ3tY7ME9BafJKDKtRUG pGcUtBRWEFAySsPZksNEZLwgYFqyMyAZVsCw7QwDs0MJ4O/vlIGn5zM4XdZLw02PnwLftWEC Oq6X0tDv+EcGLb4mCsKWpdB2Il8G1S8raBgLSyRIoUkGHtVbCfBZl4AzL1J4ZOpvGdzLryfg yIXLBAS6byC4dXSQAJejk4aG0DgBblcRCW8vNiIYtkwwYDo+zcBZowWB2VRMQV5vEsy8iVw+ 9yoBjOedFFS/60RfrceOMgfCDeOTJM5zH8BvQ49p7AlbKdxcweO6M30MzrvVw2Craz922+Jx 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um0+SoPAeiuYx9HowAx1myFYe9q0qq4nl7Cfh2b33xF3TCQS50D6WcImn8RXw0YjvEdBKXJSqZgP+A/ql5Ydz6rRoiOInW1ZmoqxQ33XjHtGEZ9zLQ8nbckU2kVuiEpwftwj2CCzSAPdgp12eF2AB2XeFg16Ooe8LHkKuhnAeNg6Kocd4lb+vSo1Ipnb7k+aj/06EF6laVu45XqHBCSdsKTkjJQ== 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: cb92173d1f0 ("locking/lockdep, cpu/hotplug: Annotate AP thread") was introduced to make lockdep_assert_cpus_held() work in AP thread. However, the annotation is too strong for that purpose. We don't have to use more than try lock annotation for that. rwsem_acquire() implies: 1. might be a waiter on contention of the lock. 2. enter to the critical section of the lock. All we need in here is to act 2, not 1. So trylock version of annotation is sufficient for that purpose. Now that dept partially relies on lockdep annotaions, dept interpets rwsem_acquire() as a potential wait and might report a deadlock by the wait. Replace it with trylock version of annotation. Signed-off-by: Byungchul Park --- kernel/cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index b08bb34b1718..3eecd0a7b5b3 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -537,7 +537,7 @@ int lockdep_is_cpus_held(void) static void lockdep_acquire_cpus_lock(void) { - rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_); + rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 1, _THIS_IP_); } static void lockdep_release_cpus_lock(void) -- 2.17.1