diff options
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 3035bebd7075..f2a5578326ad 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2345,11 +2345,22 @@ static int ptrace_stop(int exit_code, int why, unsigned long message, * will be no preemption between unlock and schedule() and so * improving the performance since the ptracer will observe that * the tracee is scheduled out once it gets on the CPU. + * + * On PREEMPT_RT locking tasklist_lock does not disable preemption. + * Therefore the task can be preempted after do_notify_parent_cldstop() + * before unlocking tasklist_lock so there is no benefit in doing this. + * + * In fact disabling preemption is harmful on PREEMPT_RT because + * the spinlock_t in cgroup_enter_frozen() must not be acquired + * with preemption disabled due to the 'sleeping' spinlock + * substitution of RT. */ - preempt_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + preempt_disable(); read_unlock(&tasklist_lock); cgroup_enter_frozen(); - preempt_enable_no_resched(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + preempt_enable_no_resched(); schedule(); cgroup_leave_frozen(true); |