Merge with the other two RCU tasks trace CPU stall commits
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 9f76a6d..e277e31 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -786,16 +786,21 @@ static void rcu_tasks_trace_postscan(void)
}
/* Show the state of a task stalling the current RCU tasks trace GP. */
-static void show_stalled_task_trace(struct task_struct *t)
+static void show_stalled_task_trace(struct task_struct *t, bool *firstreport)
{
int cpu;
+ if (*firstreport) {
+ pr_err("INFO: rcu_tasks_trace detected stalls on tasks:\n");
+ *firstreport = false;
+ }
+ // FIXME: This should attempt to use try_invoke_on_nonrunning_task().
cpu = task_cpu(t);
- pr_alert("%p: %c%c%c nesting: %d%c cpu: %d\n",
- t,
+ pr_alert("P%d: %c%c%c nesting: %d%c cpu: %d\n",
+ t->pid,
".I"[READ_ONCE(t->trc_ipi_to_cpu) > 0],
".i"[is_idle_task(t)],
- "N."[cpu < 0 || !tick_nohz_full_cpu(cpu)],
+ ".N"[cpu > 0 && tick_nohz_full_cpu(cpu)],
t->trc_reader_nesting,
" N"[!!t->trc_reader_need_end],
cpu);
@@ -831,11 +836,7 @@ static void check_all_holdout_tasks_trace(struct list_head *hop,
} else if (!needreport) {
continue;
}
- if (*firstreport) {
- pr_err("INFO: rcu_tasks_trace detected stalls on tasks:\n");
- *firstreport = false;
- }
- show_stalled_task_trace(t);
+ show_stalled_task_trace(t, firstreport);
}
if (!needreport)
return;
@@ -845,15 +846,37 @@ static void check_all_holdout_tasks_trace(struct list_head *hop,
/* Wait for grace period to complete and provide ordering. */
static void rcu_tasks_trace_postgp(void)
{
+ bool firstreport;
+ struct task_struct *g, *t;
+ LIST_HEAD(holdouts);
+ long ret;
+
// Remove the safety count.
smp_mb__before_atomic(); // Order vs. earlier atomics
atomic_dec(&trc_n_readers_need_end);
smp_mb__after_atomic(); // Order vs. later atomics
// Wait for readers.
- wait_event_idle_exclusive(trc_wait,
- atomic_read(&trc_n_readers_need_end) == 0);
-
+ for (;;) {
+ ret = wait_event_idle_exclusive_timeout(
+ trc_wait,
+ atomic_read(&trc_n_readers_need_end) == 0,
+ READ_ONCE(rcu_task_stall_timeout));
+ if (ret)
+ break; // Count reached zero.
+ for_each_process_thread(g, t) {
+ if (READ_ONCE(t->trc_reader_need_end)) {
+ trc_add_holdout(t, &holdouts);
+ }
+ }
+ firstreport = false;
+ list_for_each_entry_safe(t, g, &holdouts, trc_holdout_list)
+ if (READ_ONCE(t->trc_reader_need_end)) {
+ show_stalled_task_trace(t, &firstreport);
+ trc_del_holdout(t);
+ }
+ show_stalled_ipi_trace();
+ }
smp_mb(); // Caller's code must be ordered after wakeup.
}
