Commit-ID:  7d4d26966e0b6443c78123a8a8b602e8eaf67694
Gitweb:     http://git.kernel.org/tip/7d4d26966e0b6443c78123a8a8b602e8eaf67694
Author:     Peter Zijlstra <[email protected]>
AuthorDate: Wed, 24 Sep 2014 10:18:52 +0200
Committer:  Ingo Molnar <[email protected]>
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) <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Linus Torvalds <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 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);
                }
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