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Mon, 15 Sep 2025 21:48:27 -0700 (PDT) From: pengdonglin To: tj@kernel.org, tony.luck@intel.com, jani.nikula@linux.intel.com, ap420073@gmail.com, jv@jvosburgh.net, freude@linux.ibm.com, bcrl@kvack.org, trondmy@kernel.org, longman@redhat.com, kees@kernel.org Cc: bigeasy@linutronix.de, hdanton@sina.com, paulmck@kernel.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, linux-nfs@vger.kernel.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, netdev@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-wireless@vger.kernel.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, cgroups@vger.kernel.org, pengdonglin , Joonas Lahtinen , Tvrtko Ursulin , pengdonglin Subject: [PATCH v3 02/14] drm/i915/gt: Remove redundant rcu_read_lock/unlock() in spin_lock Date: Tue, 16 Sep 2025 12:47:23 +0800 Message-Id: <20250916044735.2316171-3-dolinux.peng@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250916044735.2316171-1-dolinux.peng@gmail.com> References: <20250916044735.2316171-1-dolinux.peng@gmail.com> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: pengdonglin Since commit a8bb74acd8efe ("rcu: Consolidate RCU-sched update-side function definitions") there is no difference between rcu_read_lock(), rcu_read_lock_bh() and rcu_read_lock_sched() in terms of RCU read section and the relevant grace period. That means that spin_lock(), which implies rcu_read_lock_sched(), also implies rcu_read_lock(). There is no need no explicitly start a RCU read section if one has already been started implicitly by spin_lock(). Simplify the code and remove the inner rcu_read_lock() invocation. Cc: Jani Nikula Cc: Joonas Lahtinen Cc: Tvrtko Ursulin Signed-off-by: pengdonglin Signed-off-by: pengdonglin --- drivers/gpu/drm/i915/gt/intel_ring_submission.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c index 2a6d79abf25b..bf73166a1337 100644 --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c @@ -392,14 +392,12 @@ static void reset_rewind(struct intel_engine_cs *engine, bool stalled) rq = NULL; spin_lock_irqsave(&engine->sched_engine->lock, flags); - rcu_read_lock(); list_for_each_entry(pos, &engine->sched_engine->requests, sched.link) { if (!__i915_request_is_complete(pos)) { rq = pos; break; } } - rcu_read_unlock(); /* * The guilty request will get skipped on a hung engine. -- 2.34.1