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-rw-r--r--fs/exec.c3
-rw-r--r--include/linux/sched.h18
2 files changed, 7 insertions, 14 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 260f89f66651..963f510a25ab 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -898,11 +898,13 @@ static int de_thread(struct task_struct *tsk)
sig->notify_count = -1; /* for exit_notify() */
for (;;) {
+ threadgroup_change_begin(tsk);
write_lock_irq(&tasklist_lock);
if (likely(leader->exit_state))
break;
__set_current_state(TASK_KILLABLE);
write_unlock_irq(&tasklist_lock);
+ threadgroup_change_end(tsk);
schedule();
if (unlikely(__fatal_signal_pending(tsk)))
goto killed;
@@ -960,6 +962,7 @@ static int de_thread(struct task_struct *tsk)
if (unlikely(leader->ptrace))
__wake_up_parent(leader, leader->parent);
write_unlock_irq(&tasklist_lock);
+ threadgroup_change_end(tsk);
release_task(leader);
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a22baf83c20c..6f950048b6e9 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2249,27 +2249,18 @@ static inline void threadgroup_change_end(struct task_struct *tsk)
*
* Lock the threadgroup @tsk belongs to. No new task is allowed to enter
* and member tasks aren't allowed to exit (as indicated by PF_EXITING) or
- * perform exec. This is useful for cases where the threadgroup needs to
- * stay stable across blockable operations.
+ * change ->group_leader/pid. This is useful for cases where the threadgroup
+ * needs to stay stable across blockable operations.
*
* fork and exit paths explicitly call threadgroup_change_{begin|end}() for
* synchronization. While held, no new task will be added to threadgroup
* and no existing live task will have its PF_EXITING set.
*
- * During exec, a task goes and puts its thread group through unusual
- * changes. After de-threading, exclusive access is assumed to resources
- * which are usually shared by tasks in the same group - e.g. sighand may
- * be replaced with a new one. Also, the exec'ing task takes over group
- * leader role including its pid. Exclude these changes while locked by
- * grabbing cred_guard_mutex which is used to synchronize exec path.
+ * de_thread() does threadgroup_change_{begin|end}() when a non-leader
+ * sub-thread becomes a new leader.
*/
static inline void threadgroup_lock(struct task_struct *tsk)
{
- /*
- * exec uses exit for de-threading nesting group_rwsem inside
- * cred_guard_mutex. Grab cred_guard_mutex first.
- */
- mutex_lock(&tsk->signal->cred_guard_mutex);
down_write(&tsk->signal->group_rwsem);
}
@@ -2282,7 +2273,6 @@ static inline void threadgroup_lock(struct task_struct *tsk)
static inline void threadgroup_unlock(struct task_struct *tsk)
{
up_write(&tsk->signal->group_rwsem);
- mutex_unlock(&tsk->signal->cred_guard_mutex);
}
#else
static inline void threadgroup_change_begin(struct task_struct *tsk) {}