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>

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index eb89e18..f032fb5 100644 (file)
--- 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);
                }