diff options
| -rw-r--r-- | include/linux/sched.h | 9 | ||||
| -rw-r--r-- | kernel/signal.c | 38 |
2 files changed, 33 insertions, 14 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index bbcfc873bd9..ca1fd31aae9 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 diff --git a/kernel/signal.c b/kernel/signal.c index b0b1ca9daa3..819fa49aa70 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1120,27 +1120,37 @@ void zap_other_threads(struct task_struct *p) /* * Must be called under rcu_read_lock() or with tasklist_lock read-held. */ +struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags) +{ + struct sighand_struct *sighand; + + for (;;) { + sighand = rcu_dereference(tsk->sighand); + if (unlikely(sighand == NULL)) + break; + + spin_lock_irqsave(&sighand->siglock, *flags); + if (likely(sighand == tsk->sighand)) + break; + spin_unlock_irqrestore(&sighand->siglock, *flags); + } + + return sighand; +} + int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) { unsigned long flags; - struct sighand_struct *sp; int ret; -retry: ret = check_kill_permission(sig, info, p); - if (!ret && sig && (sp = rcu_dereference(p->sighand))) { - spin_lock_irqsave(&sp->siglock, flags); - if (p->sighand != sp) { - spin_unlock_irqrestore(&sp->siglock, flags); - goto retry; - } - if ((atomic_read(&sp->count) == 0) || - (atomic_read(&p->usage) == 0)) { - spin_unlock_irqrestore(&sp->siglock, flags); - return -ESRCH; + + if (!ret && sig) { + ret = -ESRCH; + if (lock_task_sighand(p, &flags)) { + ret = __group_send_sig_info(sig, info, p); + unlock_task_sighand(p, &flags); } - ret = __group_send_sig_info(sig, info, p); - spin_unlock_irqrestore(&sp->siglock, flags); } return ret; |