exec: do not abuse ->cred_guard_mutex in threadgroup_lock()

[deliverable/linux.git] / include / linux / sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 54ddcb82cddfd025073f98f923490a60c9c72aaa..6f950048b6e90fd8e59b2eb376377310a38cc407 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -626,6 +626,7 @@ struct signal_struct {
 #define SIGNAL_STOP_STOPPED    0x00000001 /* job control stop in effect */
 #define SIGNAL_STOP_CONTINUED  0x00000002 /* SIGCONT since WCONTINUED reap */
 #define SIGNAL_GROUP_EXIT      0x00000004 /* group exit in progress */
+#define SIGNAL_GROUP_COREDUMP  0x00000008 /* coredump in progress */
 /*
  * Pending notifications to parent.
  */
@@ -2248,27 +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);
 }
 
@@ -2281,7 +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) {}