From 6db840fa7887980ef68a649640d506fe069eef0c Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 16 Oct 2007 23:27:23 -0700 Subject: exec: RT sub-thread can livelock and monopolize CPU on exec de_thread() yields waiting for ->group_leader to be a zombie. This deadlocks if an rt-prio execer shares the same cpu with ->group_leader. Change the code to use ->group_exit_task/notify_count mechanics. This patch certainly uglifies the code, perhaps someone can suggest something better. Signed-off-by: Oleg Nesterov Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 25f6805be5f..4c108df88a3 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -92,10 +92,9 @@ static void __exit_signal(struct task_struct *tsk) * If there is any task waiting for the group exit * then notify it: */ - if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) { + if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) wake_up_process(sig->group_exit_task); - sig->group_exit_task = NULL; - } + if (tsk == sig->curr_target) sig->curr_target = next_thread(tsk); /* @@ -827,6 +826,11 @@ static void exit_notify(struct task_struct *tsk) state = EXIT_DEAD; tsk->exit_state = state; + if (thread_group_leader(tsk) && + tsk->signal->notify_count < 0 && + tsk->signal->group_exit_task) + wake_up_process(tsk->signal->group_exit_task); + write_unlock_irq(&tasklist_lock); list_for_each_safe(_p, _n, &ptrace_dead) { -- cgit v1.2.3-18-g5258