Commit-ID: e68bbb266dcfed201d8d54a2828ef820d747f083
Gitweb: https://git.kernel.org/tip/e68bbb266dcfed201d8d54a2828ef820d747f083
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Thu, 5 Oct 2017 19:55:31 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue, 28 Nov 2017 15:51:21 -0800
rcu: Simplify rcu_eqs_{enter,exit}() non-idle task debug code
The code that checks for non-idle non-nohz_idle-usermode tasks invoking
rcu_eqs_enter() and rcu_eqs_exit() prints a considerable quantity of
helpful information. However, these checks fire rarely, so the extra
complexity is no longer worth it. This commit therefore replaces this
debug code with simple WARN_ON_ONCE() statements.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/trace/events/rcu.h | 12 +++++-------
kernel/rcu/tree.c | 24 ++----------------------
2 files changed, 7 insertions(+), 29 deletions(-)
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index d103de9..adf47c6 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -424,15 +424,13 @@ TRACE_EVENT(rcu_fqs,
* as argument: "Start" for entering dyntick-idle mode, "Startirq" for
* entering it from irq/NMI, "End" for leaving it, "Endirq" for leaving it
* to irq/NMI, "--=" for events moving towards idle, and "++=" for events
- * moving away from idle. "Error on entry: not idle task" and "Error
- * on exit: not idle task" indicate that a non-idle task is erroneously
- * toying with the idle loop.
+ * moving away from idle.
*
* These events also take a pair of numbers, which indicate the nesting
- * depth before and after the event of interest. Note that task-related
- * and interrupt-related events use two separate counters, and that the
- * "++=" and "--=" events for irq/NMI will change the counter by two,
- * otherwise by one.
+ * depth before and after the event of interest, and a third number that is
+ * the ->dynticks counter. Note that task-related and interrupt-related
+ * events use two separate counters, and that the "++=" and "--=" events
+ * for irq/NMI will change the counter by two, otherwise by one.
*/
TRACE_EVENT(rcu_dyntick,
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 46a8e06..4d374d2 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -773,17 +773,7 @@ static void rcu_eqs_enter(bool user)
lockdep_assert_irqs_disabled();
trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0, rdtp->dynticks);
- if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
- !user && !is_idle_task(current)) {
- struct task_struct *idle __maybe_unused =
- idle_task(smp_processor_id());
-
- trace_rcu_dyntick(TPS("Error on entry: not idle task"), rdtp->dynticks_nesting, 0, rdtp->dynticks);
- rcu_ftrace_dump(DUMP_ORIG);
- WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
- current->pid, current->comm,
- idle->pid, idle->comm); /* must be idle task! */
- }
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
for_each_rcu_flavor(rsp) {
rdp = this_cpu_ptr(rsp->rda);
do_nocb_deferred_wakeup(rdp);
@@ -941,17 +931,7 @@ static void rcu_eqs_exit(bool user)
rcu_dynticks_eqs_exit();
rcu_cleanup_after_idle();
trace_rcu_dyntick(TPS("End"), rdtp->dynticks_nesting, 1, rdtp->dynticks);
- if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
- !user && !is_idle_task(current)) {
- struct task_struct *idle __maybe_unused =
- idle_task(smp_processor_id());
-
- trace_rcu_dyntick(TPS("Error on exit: not idle task"), rdtp->dynticks_nesting, 1, rdtp->dynticks);
- rcu_ftrace_dump(DUMP_ORIG);
- WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
- current->pid, current->comm,
- idle->pid, idle->comm); /* must be idle task! */
- }
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
WRITE_ONCE(rdtp->dynticks_nesting, 1);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
}
--
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