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[35.188.239.129]) by smtp.gmail.com with ESMTPSA id s10-20020a05620a254a00b00745af48838bsm4347227qko.5.2023.03.15.12.39.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Mar 2023 12:39:17 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes Cc: rcu@vger.kernel.org Subject: [PATCH 6/6] rcu: Add comment to rcu_do_batch() identifying rcuoc code path Date: Wed, 15 Mar 2023 19:38:51 +0000 Message-Id: <20230315193851.8598-6-joel@joelfernandes.org> X-Mailer: git-send-email 2.40.0.rc1.284.g88254d51c5-goog In-Reply-To: <20230315193851.8598-1-joel@joelfernandes.org> References: <20230315193851.8598-1-joel@joelfernandes.org> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1760464270963570331?= X-GMAIL-MSGID: =?utf-8?q?1760464270963570331?= From: "Paul E. McKenney" This commit adds a comment to help explain why the "else" clause of the in_serving_softirq() "if" statement does not need to enforce a time limit. The reason is that this "else" clause handles rcuoc kthreads that do not block handlers for other softirq vectors. Signed-off-by: Paul E. McKenney Signed-off-by: Joel Fernandes (Google) --- kernel/rcu/tree.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8e880c09ab59..06cc6a6ad819 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2131,6 +2131,8 @@ static void rcu_do_batch(struct rcu_data *rdp) break; } } else { + // In rcuoc context, so no worries about depriving + // other softirq vectors of CPU cycles. local_bh_enable(); lockdep_assert_irqs_enabled(); cond_resched_tasks_rcu_qs();