Patch "rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     rcu-fix-missing-tick_dep_mask_rcu_exp-dependency-che.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c5168c28a38344c5e4e64ccf7c4d3bb43a5aa611
Author: Zqiang <qiang1.zhang@xxxxxxxxx>
Date:   Tue Dec 20 22:16:25 2022 +0800

    rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check
    
    [ Upstream commit db7b464df9d820186e98a65aa6a10f0d51fbf8ce ]
    
    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@xxxxxxxxx>
    Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
    Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
    Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
    Cc: Ingo Molnar <mingo@xxxxxxxxxx>
    Cc: Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
    Acked-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
    Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
    Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 19abb6c3eb73f..40e9b5a12732d 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -368,7 +368,8 @@ 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 e4e0d032126bc..378096fc8c560 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -213,6 +213,11 @@ 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;
 }