rcu: permit suppressing current grace period's CPU stall warnings

When using a kernel debugger, a long sojourn in the debugger can get
you lots of RCU CPU stall warnings once you resume.  This might not be
helpful, especially if you are using the system console.  This patch
therefore allows RCU CPU stall warnings to be suppressed, but only for
the duration of the current set of grace periods.

This differs from Jason's original patch in that it adds support for
tiny RCU and preemptible RCU, and uses a slightly different method for
suppressing the RCU CPU stall warning messages.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Jason Wessel <jason.wessel@windriver.com>

2 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 4cc5eba41616..3fa179784e18 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -178,6 +178,10 @@ static inline void rcu_sched_force_quiescent_state(void)
 {
 }
 
+static inline void rcu_cpu_stall_reset(void)
+{
+}
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
 extern int rcu_scheduler_active __read_mostly;
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index c13b85dd22bc..0726809497ba 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -36,6 +36,7 @@ extern void rcu_sched_qs(int cpu);
 extern void rcu_bh_qs(int cpu);
 extern void rcu_note_context_switch(int cpu);
 extern int rcu_needs_cpu(int cpu);
+extern void rcu_cpu_stall_reset(void);
 
 #ifdef CONFIG_TREE_PREEMPT_RCU