pid: drop irq disablement around pidmap_lock

It no longer serves any purpose now that the tasklist_lock ->
pidmap_lock ordering got eliminated.

Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250206164415.450051-6-mjguzik@gmail.com
Acked-by: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: mjguzik

kernel/pid.c

@@ -115,11 +115,10 @@ static void delayed_put_pid(struct rcu_head *rhp)
 void free_pid(struct pid *pid)
 {
 	int i;
-	unsigned long flags;
 
 	lockdep_assert_not_held(&tasklist_lock);
 
-	spin_lock_irqsave(&pidmap_lock, flags);
+	spin_lock(&pidmap_lock);
 	for (i = 0; i <= pid->level; i++) {
 		struct upid *upid = pid->numbers + i;
 		struct pid_namespace *ns = upid->ns;
@@ -142,7 +141,7 @@ void free_pid(struct pid *pid)
 		idr_remove(&ns->idr, upid->nr);
 	}
 	pidfs_remove_pid(pid);
-	spin_unlock_irqrestore(&pidmap_lock, flags);
+	spin_unlock(&pidmap_lock);
 
 	call_rcu(&pid->rcu, delayed_put_pid);
 }
@@ -210,7 +209,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
 		}
 
 		idr_preload(GFP_KERNEL);
-		spin_lock_irq(&pidmap_lock);
+		spin_lock(&pidmap_lock);
 
 		if (tid) {
 			nr = idr_alloc(&tmp->idr, NULL, tid,
@@ -237,7 +236,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
 			nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
 					      pid_max, GFP_ATOMIC);
 		}
-		spin_unlock_irq(&pidmap_lock);
+		spin_unlock(&pidmap_lock);
 		idr_preload_end();
 
 		if (nr < 0) {
@@ -271,7 +270,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
 
 	upid = pid->numbers + ns->level;
 	idr_preload(GFP_KERNEL);
-	spin_lock_irq(&pidmap_lock);
+	spin_lock(&pidmap_lock);
 	if (!(ns->pid_allocated & PIDNS_ADDING))
 		goto out_unlock;
 	pidfs_add_pid(pid);
@@ -280,18 +279,18 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
 		idr_replace(&upid->ns->idr, pid, upid->nr);
 		upid->ns->pid_allocated++;
 	}
-	spin_unlock_irq(&pidmap_lock);
+	spin_unlock(&pidmap_lock);
 	idr_preload_end();
 
 	return pid;
 
 out_unlock:
-	spin_unlock_irq(&pidmap_lock);
+	spin_unlock(&pidmap_lock);
 	idr_preload_end();
 	put_pid_ns(ns);
 
 out_free:
-	spin_lock_irq(&pidmap_lock);
+	spin_lock(&pidmap_lock);
 	while (++i <= ns->level) {
 		upid = pid->numbers + i;
 		idr_remove(&upid->ns->idr, upid->nr);
@@ -301,17 +300,17 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
 	if (ns->pid_allocated == PIDNS_ADDING)
 		idr_set_cursor(&ns->idr, 0);
 
-	spin_unlock_irq(&pidmap_lock);
+	spin_unlock(&pidmap_lock);
 
 	kmem_cache_free(ns->pid_cachep, pid);
 	return ERR_PTR(retval);
 }
 
 void disable_pid_allocation(struct pid_namespace *ns)
 {
-	spin_lock_irq(&pidmap_lock);
+	spin_lock(&pidmap_lock);
 	ns->pid_allocated &= ~PIDNS_ADDING;
-	spin_unlock_irq(&pidmap_lock);
+	spin_unlock(&pidmap_lock);
 }
 
 struct pid *find_pid_ns(int nr, struct pid_namespace *ns)