[patch V4 11/20] signal: Move MMCID exit out of sighand lock

[Thomas Gleixner <tglx@linutronix.de>]

There is no need anymore to keep this under sighand lock as the current
code and the upcoming replacement are not depending on the exit state of a
task anymore.

That allows to use a mutex in the exit path.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/sched.h |    4 ++--
 kernel/exit.c         |    1 +
 kernel/sched/core.c   |    4 ++--
 kernel/signal.c       |    2 --
 4 files changed, 5 insertions(+), 6 deletions(-)

--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2298,7 +2298,7 @@ static __always_inline void alloc_tag_re
 void sched_mm_cid_before_execve(struct task_struct *t);
 void sched_mm_cid_after_execve(struct task_struct *t);
 void sched_mm_cid_fork(struct task_struct *t);
-void sched_mm_cid_exit_signals(struct task_struct *t);
+void sched_mm_cid_exit(struct task_struct *t);
 static inline int task_mm_cid(struct task_struct *t)
 {
 	return t->mm_cid.cid;
@@ -2307,7 +2307,7 @@ static inline int task_mm_cid(struct tas
 static inline void sched_mm_cid_before_execve(struct task_struct *t) { }
 static inline void sched_mm_cid_after_execve(struct task_struct *t) { }
 static inline void sched_mm_cid_fork(struct task_struct *t) { }
-static inline void sched_mm_cid_exit_signals(struct task_struct *t) { }
+static inline void sched_mm_cid_exit(struct task_struct *t) { }
 static inline int task_mm_cid(struct task_struct *t)
 {
 	/*
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -910,6 +910,7 @@ void __noreturn do_exit(long code)
 	user_events_exit(tsk);
 
 	io_uring_files_cancel();
+	sched_mm_cid_exit(tsk);
 	exit_signals(tsk);  /* sets PF_EXITING */
 
 	seccomp_filter_release(tsk);
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -10392,7 +10392,7 @@ static inline void mm_update_cpus_allowe
 	WRITE_ONCE(mm->mm_cid.nr_cpus_allowed, weight);
 }
 
-void sched_mm_cid_exit_signals(struct task_struct *t)
+void sched_mm_cid_exit(struct task_struct *t)
 {
 	struct mm_struct *mm = t->mm;
 
@@ -10410,7 +10410,7 @@ void sched_mm_cid_exit_signals(struct ta
 /* Deactivate MM CID allocation across execve() */
 void sched_mm_cid_before_execve(struct task_struct *t)
 {
-	sched_mm_cid_exit_signals(t);
+	sched_mm_cid_exit(t);
 }
 
 /* Reactivate MM CID after successful execve() */
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3125,7 +3125,6 @@ void exit_signals(struct task_struct *ts
 	cgroup_threadgroup_change_begin(tsk);
 
 	if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
-		sched_mm_cid_exit_signals(tsk);
 		tsk->flags |= PF_EXITING;
 		cgroup_threadgroup_change_end(tsk);
 		return;
@@ -3136,7 +3135,6 @@ void exit_signals(struct task_struct *ts
 	 * From now this task is not visible for group-wide signals,
 	 * see wants_signal(), do_signal_stop().
 	 */
-	sched_mm_cid_exit_signals(tsk);
 	tsk->flags |= PF_EXITING;
 
 	cgroup_threadgroup_change_end(tsk);