linux-kernel - [PATCH 2/9] rcu: Fix missing TICK_DEP_MASK_RCU

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Date:   Wed, 15 Mar 2023 19:43:42 +0000
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Zqiang <qiang1.zhang@...el.com>,
        Anna-Maria Behnsen <anna-maria@...utronix.de>,
        Frederic Weisbecker <frederic@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        linux-trace-kernel@...r.kernel.org
Subject: [PATCH 2/9] rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check

From: Zqiang <qiang1.zhang@...el.com>

This commit adds checks for the TICK_DEP_MASK_RCU_EXP bit, thus enabling
RCU expedited grace periods to actually force-enable scheduling-clock
interrupts on holdout CPUs.

Fixes: df1e849ae455 ("rcu: Enable tick for nohz_full CPUs slow to provide expedited QS")
Signed-off-by: Zqiang <qiang1.zhang@...el.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Anna-Maria Behnsen <anna-maria@...utronix.de>
Acked-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 include/trace/events/timer.h | 3 ++-
 kernel/time/tick-sched.c     | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 2e713a7d9aa3..3e8619c72f77 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -371,7 +371,8 @@ TRACE_EVENT(itimer_expire,
 		tick_dep_name(PERF_EVENTS)		\
 		tick_dep_name(SCHED)			\
 		tick_dep_name(CLOCK_UNSTABLE)		\
-		tick_dep_name_end(RCU)
+		tick_dep_name(RCU)			\
+		tick_dep_name_end(RCU_EXP)
 
 #undef tick_dep_name
 #undef tick_dep_mask_name
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index b0e3c9205946..ba2ac1469d47 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -281,6 +281,11 @@ static bool check_tick_dependency(atomic_t *dep)
 		return true;
 	}
 
+	if (val & TICK_DEP_MASK_RCU_EXP) {
+		trace_tick_stop(0, TICK_DEP_MASK_RCU_EXP);
+		return true;
+	}
+
 	return false;
 }
 
-- 
2.40.0.rc1.284.g88254d51c5-goog