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author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-03-28 16:11:13 -0800 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-28 18:36:42 -0800 |
commit | f63ee72e0fb82e504a0489490babc7612c7cd6c2 (patch) | |
tree | 85167f8016d1f746135bf1777646a58c44376af1 /include | |
parent | aa1757f90bea3f598b6e5d04d922a6a60200f1da (diff) | |
download | kernel_samsung_smdk4412-f63ee72e0fb82e504a0489490babc7612c7cd6c2.zip kernel_samsung_smdk4412-f63ee72e0fb82e504a0489490babc7612c7cd6c2.tar.gz kernel_samsung_smdk4412-f63ee72e0fb82e504a0489490babc7612c7cd6c2.tar.bz2 |
[PATCH] introduce lock_task_sighand() helper
Add lock_task_sighand() helper and converts group_send_sig_info() to use
it. Hopefully we will have more users soon.
This patch also removes '!sighand->count' and '!p->usage' checks, I think
they both are bogus, racy and unneeded (but probably it makes sense to
restore them as BUG_ON()s).
->sighand is cleared and it's ->count is decremented in release_task() with
sighand->siglock held, so it is a bug to have '!p->usage || !->count' after
we already locked and verified it is the same. On the other hand, an
already dead task without ->sighand can have a non-zero ->usage due to
ptrace, for example.
If we read the stale value of ->sighand we must see the change after
spin_lock(), because that change was done while holding that same old
->sighand.siglock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/sched.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index bbcfc87..ca1fd31 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1225,6 +1225,15 @@ static inline void task_unlock(struct task_struct *p) spin_unlock(&p->alloc_lock); } +extern struct sighand_struct *lock_task_sighand(struct task_struct *tsk, + unsigned long *flags); + +static inline void unlock_task_sighand(struct task_struct *tsk, + unsigned long *flags) +{ + spin_unlock_irqrestore(&tsk->sighand->siglock, *flags); +} + #ifndef __HAVE_THREAD_FUNCTIONS #define task_thread_info(task) (task)->thread_info |