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| author | Oleg Nesterov <oleg@redhat.com> | 2010-06-11 01:10:18 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-06-18 10:46:57 +0200 |
| commit | 0bdd2ed4138ec04e09b4f8165981efc99e439f55 (patch) | |
| tree | 2bac5b05aa0f248b82facc0f2bc0bf705e306e05 /kernel/posix-cpu-timers.c | |
| parent | bfac7009180901f57f20a73c53c3e57b1ce75a1b (diff) | |
| download | lwn-0bdd2ed4138ec04e09b4f8165981efc99e439f55.tar.gz lwn-0bdd2ed4138ec04e09b4f8165981efc99e439f55.zip | |
sched: run_posix_cpu_timers: Don't check ->exit_state, use lock_task_sighand()
run_posix_cpu_timers() doesn't work if current has already passed
exit_notify(). This was needed to prevent the races with do_wait().
Since ea6d290c ->signal is always valid and can't go away. We can
remove the "tsk->exit_state == 0" in fastpath_timer_check() and
convert run_posix_cpu_timers() to use lock_task_sighand().
Note: it makes sense to take group_leader's sighand instead, the
sub-thread still uses CPU after release_task(). But we need more
changes to do this.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100610231018.GA25942@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/posix-cpu-timers.c')
| -rw-r--r-- | kernel/posix-cpu-timers.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index bf2a6502860a..d5dbef5e89e6 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -1272,10 +1272,6 @@ static inline int fastpath_timer_check(struct task_struct *tsk) { struct signal_struct *sig; - /* tsk == current, ensure it is safe to use ->signal/sighand */ - if (unlikely(tsk->exit_state)) - return 0; - if (!task_cputime_zero(&tsk->cputime_expires)) { struct task_cputime task_sample = { .utime = tsk->utime, @@ -1308,6 +1304,7 @@ void run_posix_cpu_timers(struct task_struct *tsk) { LIST_HEAD(firing); struct k_itimer *timer, *next; + unsigned long flags; BUG_ON(!irqs_disabled()); @@ -1318,7 +1315,8 @@ void run_posix_cpu_timers(struct task_struct *tsk) if (!fastpath_timer_check(tsk)) return; - spin_lock(&tsk->sighand->siglock); + if (!lock_task_sighand(tsk, &flags)) + return; /* * Here we take off tsk->signal->cpu_timers[N] and * tsk->cpu_timers[N] all the timers that are firing, and @@ -1340,7 +1338,7 @@ void run_posix_cpu_timers(struct task_struct *tsk) * that gets the timer lock before we do will give it up and * spin until we've taken care of that timer below. */ - spin_unlock(&tsk->sighand->siglock); + unlock_task_sighand(tsk, &flags); /* * Now that all the timers on our list have the firing flag, |