diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-13 11:25:07 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-13 11:25:07 -0700 |
commit | f7951c33f0fed14ee26651a70a46899a59a31e18 (patch) | |
tree | dff372035ceaa7b3a01e2f15c885ff0ff2510e68 /kernel/stop_machine.c | |
parent | 2406fb8d94fb17fee3ace0c09427c08825eacb16 (diff) | |
parent | 1b6266ebe3da8198e9a02fbad77bbb56e2f7ce2e (diff) | |
download | lwn-f7951c33f0fed14ee26651a70a46899a59a31e18.tar.gz lwn-f7951c33f0fed14ee26651a70a46899a59a31e18.zip |
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Thomas Gleixner:
- Cleanup and improvement of NUMA balancing
- Refactoring and improvements to the PELT (Per Entity Load Tracking)
code
- Watchdog simplification and related cleanups
- The usual pile of small incremental fixes and improvements
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
watchdog: Reduce message verbosity
stop_machine: Reflow cpu_stop_queue_two_works()
sched/numa: Move task_numa_placement() closer to numa_migrate_preferred()
sched/numa: Use group_weights to identify if migration degrades locality
sched/numa: Update the scan period without holding the numa_group lock
sched/numa: Remove numa_has_capacity()
sched/numa: Modify migrate_swap() to accept additional parameters
sched/numa: Remove unused task_capacity from 'struct numa_stats'
sched/numa: Skip nodes that are at 'hoplimit'
sched/debug: Reverse the order of printing faults
sched/numa: Use task faults only if numa_group is not yet set up
sched/numa: Set preferred_node based on best_cpu
sched/numa: Simplify load_too_imbalanced()
sched/numa: Evaluate move once per node
sched/numa: Remove redundant field
sched/debug: Show the sum wait time of a task group
sched/fair: Remove #ifdefs from scale_rt_capacity()
sched/core: Remove get_cpu() from sched_fork()
sched/cpufreq: Clarify sugov_get_util()
sched/sysctl: Remove unused sched_time_avg_ms sysctl
...
Diffstat (limited to 'kernel/stop_machine.c')
-rw-r--r-- | kernel/stop_machine.c | 41 |
1 files changed, 23 insertions, 18 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 69eb76daed34..067cb83f37ea 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -238,13 +238,24 @@ static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1, struct cpu_stopper *stopper2 = per_cpu_ptr(&cpu_stopper, cpu2); DEFINE_WAKE_Q(wakeq); int err; + retry: + /* + * The waking up of stopper threads has to happen in the same + * scheduling context as the queueing. Otherwise, there is a + * possibility of one of the above stoppers being woken up by another + * CPU, and preempting us. This will cause us to not wake up the other + * stopper forever. + */ + preempt_disable(); raw_spin_lock_irq(&stopper1->lock); raw_spin_lock_nested(&stopper2->lock, SINGLE_DEPTH_NESTING); - err = -ENOENT; - if (!stopper1->enabled || !stopper2->enabled) + if (!stopper1->enabled || !stopper2->enabled) { + err = -ENOENT; goto unlock; + } + /* * Ensure that if we race with __stop_cpus() the stoppers won't get * queued up in reverse order leading to system deadlock. @@ -255,36 +266,30 @@ retry: * It can be falsely true but it is safe to spin until it is cleared, * queue_stop_cpus_work() does everything under preempt_disable(). */ - err = -EDEADLK; - if (unlikely(stop_cpus_in_progress)) - goto unlock; + if (unlikely(stop_cpus_in_progress)) { + err = -EDEADLK; + goto unlock; + } err = 0; __cpu_stop_queue_work(stopper1, work1, &wakeq); __cpu_stop_queue_work(stopper2, work2, &wakeq); - /* - * The waking up of stopper threads has to happen - * in the same scheduling context as the queueing. - * Otherwise, there is a possibility of one of the - * above stoppers being woken up by another CPU, - * and preempting us. This will cause us to n ot - * wake up the other stopper forever. - */ - preempt_disable(); + unlock: raw_spin_unlock(&stopper2->lock); raw_spin_unlock_irq(&stopper1->lock); if (unlikely(err == -EDEADLK)) { + preempt_enable(); + while (stop_cpus_in_progress) cpu_relax(); + goto retry; } - if (!err) { - wake_up_q(&wakeq); - preempt_enable(); - } + wake_up_q(&wakeq); + preempt_enable(); return err; } |