linux-kernel - [PATCH 1/3] mm/kmemleak: Use _irq lock/unlock variants in kmemleak_scan/

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Message-Id: <20220612183301.981616-2-longman@redhat.com>
Date:   Sun, 12 Jun 2022 14:32:59 -0400
From:   Waiman Long <longman@...hat.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Waiman Long <longman@...hat.com>
Subject: [PATCH 1/3] mm/kmemleak: Use _irq lock/unlock variants in kmemleak_scan/_clear()

The kmemleak_scan() function is called only from the kmemleak scan
thread or from write to the kmemleak debugfs file. Both are in task
context and so we can directly use the simpler _irq() lock/unlock calls
instead of the more complex _irqsave/_irqrestore variants.

Similarly, kmemleak_clear() is called only from write to the kmemleak
debugfs file. The same change can be applied.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 mm/kmemleak.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index a182f5ddaf68..dad9219c972c 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1413,7 +1413,6 @@ static void scan_gray_list(void)
  */
 static void kmemleak_scan(void)
 {
-	unsigned long flags;
 	struct kmemleak_object *object;
 	struct zone *zone;
 	int __maybe_unused i;
@@ -1424,7 +1423,7 @@ static void kmemleak_scan(void)
 	/* prepare the kmemleak_object's */
 	rcu_read_lock();
 	list_for_each_entry_rcu(object, &object_list, object_list) {
-		raw_spin_lock_irqsave(&object->lock, flags);
+		raw_spin_lock_irq(&object->lock);
 #ifdef DEBUG
 		/*
 		 * With a few exceptions there should be a maximum of
@@ -1441,7 +1440,7 @@ static void kmemleak_scan(void)
 		if (color_gray(object) && get_object(object))
 			list_add_tail(&object->gray_list, &gray_list);
 
-		raw_spin_unlock_irqrestore(&object->lock, flags);
+		raw_spin_unlock_irq(&object->lock);
 	}
 	rcu_read_unlock();
 
@@ -1509,14 +1508,14 @@ static void kmemleak_scan(void)
 	 */
 	rcu_read_lock();
 	list_for_each_entry_rcu(object, &object_list, object_list) {
-		raw_spin_lock_irqsave(&object->lock, flags);
+		raw_spin_lock_irq(&object->lock);
 		if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
 		    && update_checksum(object) && get_object(object)) {
 			/* color it gray temporarily */
 			object->count = object->min_count;
 			list_add_tail(&object->gray_list, &gray_list);
 		}
-		raw_spin_unlock_irqrestore(&object->lock, flags);
+		raw_spin_unlock_irq(&object->lock);
 	}
 	rcu_read_unlock();
 
@@ -1536,7 +1535,7 @@ static void kmemleak_scan(void)
 	 */
 	rcu_read_lock();
 	list_for_each_entry_rcu(object, &object_list, object_list) {
-		raw_spin_lock_irqsave(&object->lock, flags);
+		raw_spin_lock_irq(&object->lock);
 		if (unreferenced_object(object) &&
 		    !(object->flags & OBJECT_REPORTED)) {
 			object->flags |= OBJECT_REPORTED;
@@ -1546,7 +1545,7 @@ static void kmemleak_scan(void)
 
 			new_leaks++;
 		}
-		raw_spin_unlock_irqrestore(&object->lock, flags);
+		raw_spin_unlock_irq(&object->lock);
 	}
 	rcu_read_unlock();
 
@@ -1748,15 +1747,14 @@ static int dump_str_object_info(const char *str)
 static void kmemleak_clear(void)
 {
 	struct kmemleak_object *object;
-	unsigned long flags;
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(object, &object_list, object_list) {
-		raw_spin_lock_irqsave(&object->lock, flags);
+		raw_spin_lock_irq(&object->lock);
 		if ((object->flags & OBJECT_REPORTED) &&
 		    unreferenced_object(object))
 			__paint_it(object, KMEMLEAK_GREY);
-		raw_spin_unlock_irqrestore(&object->lock, flags);
+		raw_spin_unlock_irq(&object->lock);
 	}
 	rcu_read_unlock();
 
-- 
2.31.1