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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@linux.vnet.ibm.com>
hifive-unleashed-5.1
Paul E. McKenney 2017-10-05 19:55:31 -07:00
parent 9dd238e286
commit e68bbb266d
2 changed files with 7 additions and 29 deletions
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12
include/trace/events/rcu.h
View File

@ -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,

24
kernel/rcu/tree.c
View File

@ -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);
}