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authorPaul E. McKenney <paulmck@us.ibm.com>2006-01-08 04:01:38 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 23:13:40 -0500
commit2d89c929078588aa9b9c674ef03ee9aa816b59b8 (patch)
tree129971e5c75545c53236be294f521ec6e7021a2d
parente56d090310d7625ecb43a1eeebd479f04affb48b (diff)
[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: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--kernel/signal.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 64737c72dadd..9b6fda5e87f1 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1102,18 +1102,19 @@ int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1102 1102
1103retry: 1103retry:
1104 ret = check_kill_permission(sig, info, p); 1104 ret = check_kill_permission(sig, info, p);
1105 if (!ret && sig && (sp = p->sighand)) { 1105 if (!ret && sig && (sp = rcu_dereference(p->sighand))) {
1106 if (!get_task_struct_rcu(p))
1107 return -ESRCH;
1108 spin_lock_irqsave(&sp->siglock, flags); 1106 spin_lock_irqsave(&sp->siglock, flags);
1109 if (p->sighand != sp) { 1107 if (p->sighand != sp) {
1110 spin_unlock_irqrestore(&sp->siglock, flags); 1108 spin_unlock_irqrestore(&sp->siglock, flags);
1111 put_task_struct(p);
1112 goto retry; 1109 goto retry;
1113 } 1110 }
1111 if ((atomic_read(&sp->count) == 0) ||
1112 (atomic_read(&p->usage) == 0)) {
1113 spin_unlock_irqrestore(&sp->siglock, flags);
1114 return -ESRCH;
1115 }
1114 ret = __group_send_sig_info(sig, info, p); 1116 ret = __group_send_sig_info(sig, info, p);
1115 spin_unlock_irqrestore(&sp->siglock, flags); 1117 spin_unlock_irqrestore(&sp->siglock, flags);
1116 put_task_struct(p);
1117 } 1118 }
1118 1119
1119 return ret; 1120 return ret;