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Subject[PATCH tip/core/rcu 10/10] rcu: refer RCU CPU stall-warning victims to stallwarn.txt
Date
There is some documentation on RCU CPU stall warnings contained in
Documentation/RCU/stallwarn.txt, but it will not be apparent to someone
who runs into such a warning while under time pressure. This commit
therefore adds comments preceding the printk()s pointing out the
location of this documentation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutree.c | 12 ++++++++++--
1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 5aab7da..ff21411 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -487,8 +487,11 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
rcu_print_task_stall(rnp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);

- /* OK, time to rat on our buddy... */
-
+ /*
+ * OK, time to rat on our buddy...
+ * See Documentation/RCU/stallwarn.txt for info on how to debug
+ * RCU CPU stall warnings.
+ */
printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {",
rsp->name);
rcu_for_each_leaf_node(rsp, rnp) {
@@ -517,6 +520,11 @@ static void print_cpu_stall(struct rcu_state *rsp)
unsigned long flags;
struct rcu_node *rnp = rcu_get_root(rsp);

+ /*
+ * OK, time to rat on ourselves...
+ * See Documentation/RCU/stallwarn.txt for info on how to debug
+ * RCU CPU stall warnings.
+ */
printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n",
rsp->name, smp_processor_id(), jiffies - rsp->gp_start);
trigger_all_cpu_backtrace();
--
1.7.0.6


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