Commit 2d89c929 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Linus Torvalds
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[PATCH] Simpler signal-exit concurrency handling



Some simplification in checking signal delivery against concurrent exit.
Instead of using get_task_struct_rcu(), which increments the task_struct
reference count, check the reference count after acquiring sighand lock.
Signed-off-by: default avatar"Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e56d0903
...@@ -1102,18 +1102,19 @@ int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) ...@@ -1102,18 +1102,19 @@ int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
retry: retry:
ret = check_kill_permission(sig, info, p); ret = check_kill_permission(sig, info, p);
if (!ret && sig && (sp = p->sighand)) { if (!ret && sig && (sp = rcu_dereference(p->sighand))) {
if (!get_task_struct_rcu(p))
return -ESRCH;
spin_lock_irqsave(&sp->siglock, flags); spin_lock_irqsave(&sp->siglock, flags);
if (p->sighand != sp) { if (p->sighand != sp) {
spin_unlock_irqrestore(&sp->siglock, flags); spin_unlock_irqrestore(&sp->siglock, flags);
put_task_struct(p);
goto retry; goto retry;
} }
if ((atomic_read(&sp->count) == 0) ||
(atomic_read(&p->usage) == 0)) {
spin_unlock_irqrestore(&sp->siglock, flags);
return -ESRCH;
}
ret = __group_send_sig_info(sig, info, p); ret = __group_send_sig_info(sig, info, p);
spin_unlock_irqrestore(&sp->siglock, flags); spin_unlock_irqrestore(&sp->siglock, flags);
put_task_struct(p);
} }
return ret; return ret;
......
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