From b2b2cbc4b2a2f389442549399a993a8306420baf Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 21 Dec 2006 21:28:40 -0700 Subject: [PATCH] Fix reparenting to the same thread group. (take 2) This patch fixes the case when we reparent to a different thread in the same thread group. This modifies the code so that we do not send signals and do not change the signal to send to SIGCHLD unless we have change the thread group of our parents. It also suppresses sending pdeath_sig in this cas as well since the result of geppid doesn't change. Thanks to Oleg for spotting my bug of only fixing this for non-ptraced tasks. Signed-off-by: Eric W. Biederman Cc: Mike Galbraith Cc: Albert Cahalan Cc: Andrew Morton Cc: Roland McGrath Cc: Ingo Molnar Cc: Coywolf Qi Hunt Acked-by: Oleg Nesterov Signed-off-by: Linus Torvalds --- kernel/exit.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 85917c2bf06..46cf6b68146 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -597,14 +597,6 @@ choose_new_parent(struct task_struct *p, struct task_struct *reaper) static void reparent_thread(struct task_struct *p, struct task_struct *father, int traced) { - /* We don't want people slaying init. */ - if (p->exit_signal != -1) - p->exit_signal = SIGCHLD; - - if (p->pdeath_signal) - /* We already hold the tasklist_lock here. */ - group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); - /* Move the child from its dying parent to the new one. */ if (unlikely(traced)) { /* Preserve ptrace links if someone else is tracing this child. */ @@ -620,13 +612,7 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced) p->parent = p->real_parent; add_parent(p); - /* If we'd notified the old parent about this child's death, - * also notify the new parent. - */ - if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && - thread_group_empty(p)) - do_notify_parent(p, p->exit_signal); - else if (p->state == TASK_TRACED) { + if (p->state == TASK_TRACED) { /* * If it was at a trace stop, turn it into * a normal stop since it's no longer being @@ -636,6 +622,27 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced) } } + /* If this is a threaded reparent there is no need to + * notify anyone anything has happened. + */ + if (p->real_parent->group_leader == father->group_leader) + return; + + /* We don't want people slaying init. */ + if (p->exit_signal != -1) + p->exit_signal = SIGCHLD; + + if (p->pdeath_signal) + /* We already hold the tasklist_lock here. */ + group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); + + /* If we'd notified the old parent about this child's death, + * also notify the new parent. + */ + if (!traced && p->exit_state == EXIT_ZOMBIE && + p->exit_signal != -1 && thread_group_empty(p)) + do_notify_parent(p, p->exit_signal); + /* * process group orphan check * Case ii: Our child is in a different pgrp -- cgit v1.2.3-18-g5258