Commit-ID: c5ebe66ce774126b888617cab658f6556d23365e
Gitweb: http://git.kernel.org/tip/c5ebe66ce774126b888617cab658f6556d23365e
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 19 Jun 2017 10:32:23 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 17 Aug 2017 07:26:06 -0700
rcu: Add event tracing to ->gp_tasks update at GP start
There is currently event tracing to track when a task is preempted
within a preemptible RCU read-side critical section, and also when that
task subsequently reaches its outermost rcu_read_unlock(), but none
indicating when a new grace period starts when that grace period must
wait on pre-existing readers that have been been preempted at least once
since the beginning of their current RCU read-side critical sections.
This commit therefore adds an event trace at grace-period start in
the case where there are such readers. Note that only the first
reader in the list is traced.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
kernel/rcu/tree_plugin.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 14ba496..3e3f92e 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -636,10 +636,17 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp)
*/
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
{
+ struct task_struct *t;
+
RCU_LOCKDEP_WARN(preemptible(), "rcu_preempt_check_blocked_tasks() invoked with preemption enabled!!!\n");
WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp));
- if (rcu_preempt_has_tasks(rnp))
+ if (rcu_preempt_has_tasks(rnp)) {
rnp->gp_tasks = rnp->blkd_tasks.next;
+ t = container_of(rnp->gp_tasks, struct task_struct,
+ rcu_node_entry);
+ trace_rcu_unlock_preempted_task(TPS("rcu_preempt-GPS"),
+ rnp->gpnum, t->pid);
+ }
WARN_ON_ONCE(rnp->qsmask);
}
--
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