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Mon, 15 Sep 2025 21:49:33 -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 , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , pengdonglin Subject: [PATCH v3 12/14] net: amt: Remove redundant rcu_read_lock/unlock() in spin_lock Date: Tue, 16 Sep 2025 12:47:33 +0800 Message-Id: <20250916044735.2316171-13-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: Taehee Yoo Cc: Andrew Lunn Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Signed-off-by: pengdonglin Signed-off-by: pengdonglin --- drivers/net/amt.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/drivers/net/amt.c b/drivers/net/amt.c index ed86537b2f61..aaed9fbc7526 100644 --- a/drivers/net/amt.c +++ b/drivers/net/amt.c @@ -295,7 +295,6 @@ static void amt_source_work(struct work_struct *work) tunnel = gnode->tunnel_list; spin_lock_bh(&tunnel->lock); - rcu_read_lock(); if (gnode->filter_mode == MCAST_INCLUDE) { amt_destroy_source(snode); if (!gnode->nr_sources) @@ -306,7 +305,6 @@ static void amt_source_work(struct work_struct *work) */ snode->status = AMT_SOURCE_STATUS_D_FWD; } - rcu_read_unlock(); spin_unlock_bh(&tunnel->lock); } @@ -426,7 +424,6 @@ static void amt_group_work(struct work_struct *work) goto out; } - rcu_read_lock(); for (i = 0; i < buckets; i++) { hlist_for_each_entry_safe(snode, t, &gnode->sources[i], node) { @@ -443,7 +440,6 @@ static void amt_group_work(struct work_struct *work) amt_del_group(amt, gnode); else gnode->filter_mode = MCAST_INCLUDE; - rcu_read_unlock(); spin_unlock_bh(&tunnel->lock); out: dev_put(amt->dev); @@ -1327,11 +1323,9 @@ static void amt_clear_groups(struct amt_tunnel_list *tunnel) int i; spin_lock_bh(&tunnel->lock); - rcu_read_lock(); for (i = 0; i < amt->hash_buckets; i++) hlist_for_each_entry_safe(gnode, t, &tunnel->groups[i], node) amt_del_group(amt, gnode); - rcu_read_unlock(); spin_unlock_bh(&tunnel->lock); } @@ -1343,11 +1337,9 @@ static void amt_tunnel_expire(struct work_struct *work) struct amt_dev *amt = tunnel->amt; spin_lock_bh(&amt->lock); - rcu_read_lock(); list_del_rcu(&tunnel->list); amt->nr_tunnels--; amt_clear_groups(tunnel); - rcu_read_unlock(); spin_unlock_bh(&amt->lock); kfree_rcu(tunnel, rcu); } -- 2.34.1