5d8f72b55c
try_to_freeze_tasks() and cgroup_freezer rely on scheduler locks to ensure that a task doing STOPPED/TRACED -> RUNNING transition can't escape freezing. This mostly works, but ptrace_stop() does not necessarily call schedule(), it can change task->state back to RUNNING and check freezing() without any lock/barrier in between. We could add the necessary barrier, but this patch changes ptrace_stop() and do_signal_stop() to use freezable_schedule(). This fixes the race, freezer_count() and freezer_should_skip() carefully avoid the race. And this simplifies the code, try_to_freeze_tasks/update_if_frozen no longer need to use task_is_stopped_or_traced() checks with the non trivial assumptions. We can rely on the mechanism which was specially designed to mark the sleeping task as "frozen enough". v2: As Tejun pointed out, we can also change get_signal_to_deliver() and move try_to_freeze() up before 'relock' label. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> |
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| .. | ||
| Kconfig | ||
| Makefile | ||
| autosleep.c | ||
| block_io.c | ||
| console.c | ||
| hibernate.c | ||
| main.c | ||
| power.h | ||
| poweroff.c | ||
| process.c | ||
| qos.c | ||
| snapshot.c | ||
| suspend.c | ||
| suspend_test.c | ||
| swap.c | ||
| user.c | ||
| wakelock.c | ||