diff options
| author | Tejun Heo <tj@kernel.org> | 2011-06-02 11:14:00 +0200 |
|---|---|---|
| committer | Oleg Nesterov <oleg@redhat.com> | 2011-06-04 18:17:11 +0200 |
| commit | 6dfca32984237a8a011b5bf367e53341a265b2a4 (patch) | |
| tree | a879c682f00921959ee28b563b9024c0ac54f861 /kernel/signal.c | |
| parent | 3759a0d94c18764247b66511d1038f2b93aa95de (diff) | |
job control: make task_clear_jobctl_pending() clear TRAPPING automatically
JOBCTL_TRAPPING indicates that ptracer is waiting for tracee to
(re)transit into TRACED. task_clear_jobctl_pending() must be called
when either tracee enters TRACED or the transition is cancelled for
some reason. The former is achieved by explicitly calling
task_clear_jobctl_pending() in ptrace_stop() and the latter by calling
it at the end of do_signal_stop().
Calling task_clear_jobctl_trapping() at the end of do_signal_stop()
limits the scope TRAPPING can be used and is fragile in that seemingly
unrelated changes to tracee's control flow can lead to stuck TRAPPING.
We already have task_clear_jobctl_pending() calls on those cancelling
events to clear JOBCTL_STOP_PENDING. Cancellations can be handled by
making those call sites use JOBCTL_PENDING_MASK instead and updating
task_clear_jobctl_pending() such that task_clear_jobctl_trapping() is
called automatically if no stop/trap is pending.
This patch makes the above changes and removes the fallback
task_clear_jobctl_trapping() call from do_signal_stop().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 288d952fa3b8..637a171b65b6 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -253,6 +253,9 @@ static void task_clear_jobctl_trapping(struct task_struct *task) * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other * STOP bits are cleared together. * + * If clearing of @mask leaves no stop or trap pending, this function calls + * task_clear_jobctl_trapping(). + * * CONTEXT: * Must be called with @task->sighand->siglock held. */ @@ -264,6 +267,9 @@ void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask) mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED; task->jobctl &= ~mask; + + if (!(task->jobctl & JOBCTL_PENDING_MASK)) + task_clear_jobctl_trapping(task); } /** @@ -933,7 +939,7 @@ static void complete_signal(int sig, struct task_struct *p, int group) signal->group_stop_count = 0; t = p; do { - task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING); + task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); sigaddset(&t->pending.signal, SIGKILL); signal_wake_up(t, 1); } while_each_thread(p, t); @@ -1168,7 +1174,7 @@ int zap_other_threads(struct task_struct *p) p->signal->group_stop_count = 0; while_each_thread(p, t) { - task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING); + task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); count++; /* Don't bother with already dead threads */ @@ -1964,9 +1970,6 @@ retry: goto retry; } - /* PTRACE_ATTACH might have raced with task killing, clear trapping */ - task_clear_jobctl_trapping(current); - spin_unlock_irq(¤t->sighand->siglock); tracehook_finish_jctl(); |