Commit-ID: 61f38db3e3c0e4c3be0858750e2cabeadaecac0c
Gitweb: http://git.kernel.org/tip/61f38db3e3c0e4c3be0858750e2cabeadaecac0c
Author: Rik van Riel <riel@xxxxxxxxxx>
AuthorDate: Sat, 26 Apr 2014 23:15:35 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon, 19 May 2014 10:52:04 -0700
rcu: Provide API to suppress stall warnings while sysrc runs
Some sysrq handlers can run for a long time, because they dump a lot
of data onto a serial console. Having RCU stall warnings pop up in
the middle of them only makes the problem worse.
This commit provides rcu_sysrq_start() and rcu_sysrq_end() APIs to
temporarily suppress RCU CPU stall warnings while a sysrq request is
handled.
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
[ paulmck: Fix TINY_RCU build error. ]
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/rcupdate.h | 12 ++++++++++++
kernel/rcu/update.c | 12 ++++++++++++
2 files changed, 24 insertions(+)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 9ccd644..5a75d19 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -248,6 +248,18 @@ void rcu_idle_exit(void);
void rcu_irq_enter(void);
void rcu_irq_exit(void);
+#ifdef CONFIG_RCU_STALL_COMMON
+void rcu_sysrq_start(void);
+void rcu_sysrq_end(void);
+#else /* #ifdef CONFIG_RCU_STALL_COMMON */
+static inline void rcu_sysrq_start(void)
+{
+}
+static inline void rcu_sysrq_end(void)
+{
+}
+#endif /* #else #ifdef CONFIG_RCU_STALL_COMMON */
+
#ifdef CONFIG_RCU_USER_QS
void rcu_user_enter(void);
void rcu_user_exit(void);
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index ed7a0d7..a2aeb4d 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -320,6 +320,18 @@ int rcu_jiffies_till_stall_check(void)
return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
}
+void rcu_sysrq_start(void)
+{
+ if (!rcu_cpu_stall_suppress)
+ rcu_cpu_stall_suppress = 2;
+}
+
+void rcu_sysrq_end(void)
+{
+ if (rcu_cpu_stall_suppress == 2)
+ rcu_cpu_stall_suppress = 0;
+}
+
static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
{
rcu_cpu_stall_suppress = 1;
--
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