Commit-ID: f22ce09157239aab08eae99c678ef664f71a9097
Gitweb: https://git.kernel.org/tip/f22ce09157239aab08eae99c678ef664f71a9097
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Fri, 1 Sep 2017 14:40:54 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon, 9 Oct 2017 14:25:17 -0700
rcu: Suppress RCU CPU stall warnings while dumping trace
Currently, RCU emits Suppress RCU CPU stall warnings during its
automatically initiated ftrace_dump() calls after detecting an error
condition, which can result in excessively excessive console output
and lost trace events. This commit therefore suppresses RCU CPU stall
warnings across any of these ftrace_dump() calls.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/rcu.h | 17 +++++++++++++++++
kernel/rcu/update.c | 1 +
2 files changed, 18 insertions(+)
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index b8729eb..59c471d 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -203,6 +203,21 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
extern int rcu_cpu_stall_suppress;
int rcu_jiffies_till_stall_check(void);
+#define rcu_ftrace_dump_stall_suppress() \
+do { \
+ if (!rcu_cpu_stall_suppress) \
+ rcu_cpu_stall_suppress = 3; \
+} while (0)
+
+#define rcu_ftrace_dump_stall_unsuppress() \
+do { \
+ if (rcu_cpu_stall_suppress == 3) \
+ rcu_cpu_stall_suppress = 0; \
+} while (0)
+
+#else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */
+#define rcu_ftrace_dump_stall_suppress()
+#define rcu_ftrace_dump_stall_unsuppress()
#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
/*
@@ -222,7 +237,9 @@ do { \
if (!atomic_read(&___rfd_beenhere) && \
!atomic_xchg(&___rfd_beenhere, 1)) { \
tracing_off(); \
+ rcu_ftrace_dump_stall_suppress(); \
ftrace_dump(oops_dump_mode); \
+ rcu_ftrace_dump_stall_unsuppress(); \
} \
} while (0)
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 5033b66..3dc8efb 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -494,6 +494,7 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
#endif
int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
+EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);
static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
module_param(rcu_cpu_stall_suppress, int, 0644);
--
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