X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=kernel%2Fexit.c;h=ee5a8786c3d226ade9d46fa4238b5a8536f59c5f;hp=d0b7d988f8735beb6e1e7b5f7b42ecbd04b91bf5;hb=5d53f2c26f29e917b401e8bb539ba85e52725e8c;hpb=3c00303206c3a1ccd86579efdc90bc35f140962e

diff --git a/kernel/exit.c b/kernel/exit.c
index d0b7d988f873..ee5a8786c3d2 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -734,9 +734,6 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
 				struct list_head *dead)
 {
 	list_move_tail(&p->sibling, &p->real_parent->children);
-
-	if (p->exit_state == EXIT_DEAD)
-		return;
 	/*
 	 * If this is a threaded reparent there is no need to
 	 * notify anyone anything has happened.
@@ -744,9 +741,19 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
 	if (same_thread_group(p->real_parent, father))
 		return;
 
-	/* We don't want people slaying init.  */
+	/*
+	 * We don't want people slaying init.
+	 *
+	 * Note: we do this even if it is EXIT_DEAD, wait_task_zombie()
+	 * can change ->exit_state to EXIT_ZOMBIE. If this is the final
+	 * state, do_notify_parent() was already called and ->exit_signal
+	 * doesn't matter.
+	 */
 	p->exit_signal = SIGCHLD;
 
+	if (p->exit_state == EXIT_DEAD)
+		return;
+
 	/* If it has exited notify the new parent about this child's death. */
 	if (!p->ptrace &&
 	    p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
@@ -819,25 +826,6 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
 	if (group_dead)
 		kill_orphaned_pgrp(tsk->group_leader, NULL);
 
-	/* Let father know we died
-	 *
-	 * Thread signals are configurable, but you aren't going to use
-	 * that to send signals to arbitrary processes.
-	 * That stops right now.
-	 *
-	 * If the parent exec id doesn't match the exec id we saved
-	 * when we started then we know the parent has changed security
-	 * domain.
-	 *
-	 * If our self_exec id doesn't match our parent_exec_id then
-	 * we have changed execution domain as these two values started
-	 * the same after a fork.
-	 */
-	if (thread_group_leader(tsk) && tsk->exit_signal != SIGCHLD &&
-	    (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
-	     tsk->self_exec_id != tsk->parent_exec_id))
-		tsk->exit_signal = SIGCHLD;
-
 	if (unlikely(tsk->ptrace)) {
 		int sig = thread_group_leader(tsk) &&
 				thread_group_empty(tsk) &&
@@ -1038,6 +1026,22 @@ NORET_TYPE void do_exit(long code)
 
 	preempt_disable();
 	exit_rcu();
+
+	/*
+	 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
+	 * when the following two conditions become true.
+	 *   - There is race condition of mmap_sem (It is acquired by
+	 *     exit_mm()), and
+	 *   - SMI occurs before setting TASK_RUNINNG.
+	 *     (or hypervisor of virtual machine switches to other guest)
+	 *  As a result, we may become TASK_RUNNING after becoming TASK_DEAD
+	 *
+	 * To avoid it, we have to wait for releasing tsk->pi_lock which
+	 * is held by try_to_wake_up()
+	 */
+	smp_mb();
+	raw_spin_unlock_wait(&tsk->pi_lock);
+
 	/* causes final put_task_struct in finish_task_switch(). */
 	tsk->state = TASK_DEAD;
 	schedule();
@@ -1134,17 +1138,28 @@ static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
 		task_pid_type(p, wo->wo_type) == wo->wo_pid;
 }
 
-static int eligible_child(struct wait_opts *wo, struct task_struct *p)
+static int
+eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
 {
 	if (!eligible_pid(wo, p))
 		return 0;
-	/* Wait for all children (clone and not) if __WALL is set;
-	 * otherwise, wait for clone children *only* if __WCLONE is
-	 * set; otherwise, wait for non-clone children *only*.  (Note:
-	 * A "clone" child here is one that reports to its parent
-	 * using a signal other than SIGCHLD.) */
-	if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
-	    && !(wo->wo_flags & __WALL))
+
+	/*
+	 * Wait for all children (clone and not) if __WALL is set or
+	 * if it is traced by us.
+	 */
+	if (ptrace || (wo->wo_flags & __WALL))
+		return 1;
+
+	/*
+	 * Otherwise, wait for clone children *only* if __WCLONE is set;
+	 * otherwise, wait for non-clone children *only*.
+	 *
+	 * Note: a "clone" child here is one that reports to its parent
+	 * using a signal other than SIGCHLD, or a non-leader thread which
+	 * we can only see if it is traced by us.
+	 */
+	if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
 		return 0;
 
 	return 1;
@@ -1521,7 +1536,7 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
 static int wait_consider_task(struct wait_opts *wo, int ptrace,
 				struct task_struct *p)
 {
-	int ret = eligible_child(wo, p);
+	int ret = eligible_child(wo, ptrace, p);
 	if (!ret)
 		return ret;
 
@@ -1540,8 +1555,15 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
 	}
 
 	/* dead body doesn't have much to contribute */
-	if (p->exit_state == EXIT_DEAD)
+	if (unlikely(p->exit_state == EXIT_DEAD)) {
+		/*
+		 * But do not ignore this task until the tracer does
+		 * wait_task_zombie()->do_notify_parent().
+		 */
+		if (likely(!ptrace) && unlikely(ptrace_reparented(p)))
+			wo->notask_error = 0;
 		return 0;
+	}
 
 	/* slay zombie? */
 	if (p->exit_state == EXIT_ZOMBIE) {