diff options
author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2010-03-24 18:34:10 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2010-04-02 20:12:03 +0200 |
commit | 0017d735092844118bef006696a750a0e4ef6ebd (patch) | |
tree | 8ed1540aaeb63da726f93da12950a8eaa0e0a3e0 /include/linux/sched.h | |
parent | 9084bb8246ea935b98320554229e2f371f7f52fa (diff) | |
download | kernel_samsung_espresso10-0017d735092844118bef006696a750a0e4ef6ebd.zip kernel_samsung_espresso10-0017d735092844118bef006696a750a0e4ef6ebd.tar.gz kernel_samsung_espresso10-0017d735092844118bef006696a750a0e4ef6ebd.tar.bz2 |
sched: Fix TASK_WAKING vs fork deadlock
Oleg noticed a few races with the TASK_WAKING usage on fork.
- since TASK_WAKING is basically a spinlock, it should be IRQ safe
- since we set TASK_WAKING (*) without holding rq->lock it could
be there still is a rq->lock holder, thereby not actually
providing full serialization.
(*) in fact we clear PF_STARTING, which in effect enables TASK_WAKING.
Cure the second issue by not setting TASK_WAKING in sched_fork(), but
only temporarily in wake_up_new_task() while calling select_task_rq().
Cure the first by holding rq->lock around the select_task_rq() call,
this will disable IRQs, this however requires that we push down the
rq->lock release into select_task_rq_fair()'s cgroup stuff.
Because select_task_rq_fair() still needs to drop the rq->lock we
cannot fully get rid of TASK_WAKING.
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/sched.h')
-rw-r--r-- | include/linux/sched.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 8bea407..fb6c188 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1046,7 +1046,8 @@ struct sched_class { void (*put_prev_task) (struct rq *rq, struct task_struct *p); #ifdef CONFIG_SMP - int (*select_task_rq)(struct task_struct *p, int sd_flag, int flags); + int (*select_task_rq)(struct rq *rq, struct task_struct *p, + int sd_flag, int flags); void (*pre_schedule) (struct rq *this_rq, struct task_struct *task); void (*post_schedule) (struct rq *this_rq); |