[tip:sched/core] sched, smp: Correctly deal with nested sleeps

tip-bot for Peter Zijlstra
2014-10-28T11:12:03Z

Commit-ID: 7d4d26966e0b6443c78123a8a8b602e8eaf67694
Gitweb: http://git.kernel.org/tip/7d4d26966e0b6443c78123a8a8b602e8eaf67694
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Wed, 24 Sep 2014 10:18:52 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 Oct 2014 10:56:24 +0100

sched, smp: Correctly deal with nested sleeps

smp_hotplug_thread::{setup,unpark} functions can sleep too, so be
consistent and do the same for all callbacks.

__might_sleep+0x74/0x80
kmem_cache_alloc_trace+0x4e/0x1c0
perf_event_alloc+0x55/0x450
perf_event_create_kernel_counter+0x2f/0x100
watchdog_nmi_enable+0x8d/0x160
watchdog_enable+0x45/0x90
smpboot_thread_fn+0xec/0x2b0
kthread+0xe4/0x100
ret_from_fork+0x7c/0xb0

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140924082242.392279328@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/smpboot.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index eb89e18..f032fb5 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -110,7 +110,7 @@ static int smpboot_thread_fn(void *data)
set_current_state(TASK_INTERRUPTIBLE);
preempt_disable();
if (kthread_should_stop()) {
- set_current_state(TASK_RUNNING);
+ __set_current_state(TASK_RUNNING);
preempt_enable();
if (ht->cleanup)
ht->cleanup(td->cpu, cpu_online(td->cpu));
@@ -136,26 +136,27 @@ static int smpboot_thread_fn(void *data)
/* Check for state change setup */
switch (td->status) {
case HP_THREAD_NONE:
+ __set_current_state(TASK_RUNNING);
preempt_enable();
if (ht->setup)
ht->setup(td->cpu);
td->status = HP_THREAD_ACTIVE;
- preempt_disable();
- break;
+ continue;
+
case HP_THREAD_PARKED:
+ __set_current_state(TASK_RUNNING);
preempt_enable();
if (ht->unpark)
ht->unpark(td->cpu);
td->status = HP_THREAD_ACTIVE;
- preempt_disable();
- break;
+ continue;
}

if (!ht->thread_should_run(td->cpu)) {
- preempt_enable();
+ preempt_enable_no_resched();
schedule();
} else {
- set_current_state(TASK_RUNNING);
+ __set_current_state(TASK_RUNNING);
preempt_enable();
ht->thread_fn(td->cpu);
}