This commit add TICK_DEP_MASK_RCU_EXP dependency check in
check_tick_dependency(), fix commit df1e849ae4559 ("rcu: Enable
tick for nohz_full CPUs slow to provide expedited QS").

Signed-off-by: Zqiang <qiang1.zhang@intel.com>
---
 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;
 }
 
-- 
2.25.1

On Tue, Dec 20, 2022 at 10:16:25PM +0800, Zqiang wrote:
> This commit add TICK_DEP_MASK_RCU_EXP dependency check in
> check_tick_dependency(), fix commit df1e849ae4559 ("rcu: Enable
> tick for nohz_full CPUs slow to provide expedited QS").
> 
> Signed-off-by: Zqiang <qiang1.zhang@intel.com>

Again, good eyes, thank you!!!

I have queued this for further review and testing, given that it affects
pretty much only RCU.  However, if someone else would rather take it:

Acked-by: Paul E. McKenney <paulmck@kernel.org>

							Thanx, Paul

------------------------------------------------------------------------

commit f22caef6cda5ed19a55ec2e703f60f1fa85e52bc
Author: Zqiang <qiang1.zhang@intel.com>
Date:   Tue Dec 20 22:16:25 2022 +0800

    rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check
    
    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@intel.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Anna-Maria Behnsen <anna-maria@linutronix.de>
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 2e713a7d9aa3a..3e8619c72f774 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 b0e3c9205946f..ba2ac1469d473 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;
 }

On Wed, Dec 21, 2022 at 12:16:34PM -0800, Paul E. McKenney wrote:
> On Tue, Dec 20, 2022 at 10:16:25PM +0800, Zqiang wrote:
> > This commit add TICK_DEP_MASK_RCU_EXP dependency check in
> > check_tick_dependency(), fix commit df1e849ae4559 ("rcu: Enable
> > tick for nohz_full CPUs slow to provide expedited QS").
> > 
> > Signed-off-by: Zqiang <qiang1.zhang@intel.com>
> 
> Again, good eyes, thank you!!!
> 
> I have queued this for further review and testing, given that it affects
> pretty much only RCU.  However, if someone else would rather take it:
> 
> Acked-by: Paul E. McKenney <paulmck@kernel.org>


Thanks for picking it up! Please also add the following tags:

Fixes: df1e849ae455 ("rcu: Enable tick for nohz_full CPUs slow to provide expedited QS")
Acked-by: Frederic Weisbecker <frederic@kernel.org>

Thanks!

On Sat, Jan 07, 2023 at 10:39:22PM +0100, Frederic Weisbecker wrote:
> On Wed, Dec 21, 2022 at 12:16:34PM -0800, Paul E. McKenney wrote:
> > On Tue, Dec 20, 2022 at 10:16:25PM +0800, Zqiang wrote:
> > > This commit add TICK_DEP_MASK_RCU_EXP dependency check in
> > > check_tick_dependency(), fix commit df1e849ae4559 ("rcu: Enable
> > > tick for nohz_full CPUs slow to provide expedited QS").
> > > 
> > > Signed-off-by: Zqiang <qiang1.zhang@intel.com>
> > 
> > Again, good eyes, thank you!!!
> > 
> > I have queued this for further review and testing, given that it affects
> > pretty much only RCU.  However, if someone else would rather take it:
> > 
> > Acked-by: Paul E. McKenney <paulmck@kernel.org>
> 
> Thanks for picking it up! Please also add the following tags:
> 
> Fixes: df1e849ae455 ("rcu: Enable tick for nohz_full CPUs slow to provide expedited QS")
> Acked-by: Frederic Weisbecker <frederic@kernel.org>

Thank you for looking it over!  I will apply these on my next rebase.

							Thanx, Paul