From bab4a34afc301fdb81b6ea0e3098d96fc356e03a Mon Sep 17 00:00:00 2001
From: Catalin Marinas <catalin.marinas@arm.com>
Date: Fri, 26 Jun 2009 17:38:26 +0100
Subject: kmemleak: Simplify the reports logged by the scanning thread

Because of false positives, the memory scanning thread may print too
much information. This patch changes the scanning thread to only print
the number of newly suspected leaks. Further information can be read
from the /sys/kernel/debug/kmemleak file.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
 mm/kmemleak.c | 61 ++++++++++++++++-------------------------------------------
 1 file changed, 16 insertions(+), 45 deletions(-)

(limited to 'mm/kmemleak.c')

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index a38418a95d33..4130a4889fa9 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -278,15 +278,6 @@ static int color_gray(const struct kmemleak_object *object)
 	return object->min_count != -1 && object->count >= object->min_count;
 }
 
-/*
- * Objects are considered referenced if their color is gray and they have not
- * been deleted.
- */
-static int referenced_object(struct kmemleak_object *object)
-{
-	return (object->flags & OBJECT_ALLOCATED) && color_gray(object);
-}
-
 /*
  * Objects are considered unreferenced only if their color is white, they have
  * not be deleted and have a minimum age to avoid false positives caused by
@@ -299,38 +290,23 @@ static int unreferenced_object(struct kmemleak_object *object)
 }
 
 /*
- * Printing of the (un)referenced objects information, either to the seq file
- * or to the kernel log. The print_referenced/print_unreferenced functions
- * must be called with the object->lock held.
+ * Printing of the unreferenced objects information to the seq file. The
+ * print_unreferenced function must be called with the object->lock held.
  */
-#define print_helper(seq, x...)	do {	\
-	struct seq_file *s = (seq);	\
-	if (s)				\
-		seq_printf(s, x);	\
-	else				\
-		pr_info(x);		\
-} while (0)
-
-static void print_referenced(struct kmemleak_object *object)
-{
-	pr_info("referenced object 0x%08lx (size %zu)\n",
-		object->pointer, object->size);
-}
-
 static void print_unreferenced(struct seq_file *seq,
 			       struct kmemleak_object *object)
 {
 	int i;
 
-	print_helper(seq, "unreferenced object 0x%08lx (size %zu):\n",
-		     object->pointer, object->size);
-	print_helper(seq, "  comm \"%s\", pid %d, jiffies %lu\n",
-		     object->comm, object->pid, object->jiffies);
-	print_helper(seq, "  backtrace:\n");
+	seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
+		   object->pointer, object->size);
+	seq_printf(seq, "  comm \"%s\", pid %d, jiffies %lu\n",
+		   object->comm, object->pid, object->jiffies);
+	seq_printf(seq, "  backtrace:\n");
 
 	for (i = 0; i < object->trace_len; i++) {
 		void *ptr = (void *)object->trace[i];
-		print_helper(seq, "    [<%p>] %pS\n", ptr, ptr);
+		seq_printf(seq, "    [<%p>] %pS\n", ptr, ptr);
 	}
 }
 
@@ -571,8 +547,6 @@ static void delete_object(unsigned long ptr)
 	 * cannot be freed when it is being scanned.
 	 */
 	spin_lock_irqsave(&object->lock, flags);
-	if (object->flags & OBJECT_REPORTED)
-		print_referenced(object);
 	object->flags &= ~OBJECT_ALLOCATED;
 	spin_unlock_irqrestore(&object->lock, flags);
 	put_object(object);
@@ -1073,33 +1047,30 @@ static int kmemleak_scan_thread(void *arg)
 	while (!kthread_should_stop()) {
 		struct kmemleak_object *object;
 		signed long timeout = jiffies_scan_wait;
+		int new_leaks = 0;
 
 		mutex_lock(&scan_mutex);
 
 		kmemleak_scan();
-		reported_leaks = 0;
 
 		rcu_read_lock();
 		list_for_each_entry_rcu(object, &object_list, object_list) {
 			unsigned long flags;
 
-			if (reported_leaks >= REPORTS_NR)
-				break;
 			spin_lock_irqsave(&object->lock, flags);
-			if (!(object->flags & OBJECT_REPORTED) &&
-			    unreferenced_object(object)) {
-				print_unreferenced(NULL, object);
+			if (unreferenced_object(object) &&
+			    !(object->flags & OBJECT_REPORTED)) {
 				object->flags |= OBJECT_REPORTED;
-				reported_leaks++;
-			} else if ((object->flags & OBJECT_REPORTED) &&
-				   referenced_object(object)) {
-				print_referenced(object);
-				object->flags &= ~OBJECT_REPORTED;
+				new_leaks++;
 			}
 			spin_unlock_irqrestore(&object->lock, flags);
 		}
 		rcu_read_unlock();
 
+		if (new_leaks)
+			pr_info("%d new suspected memory leaks (see "
+				"/sys/kernel/debug/kmemleak)\n", new_leaks);
+
 		mutex_unlock(&scan_mutex);
 		/* wait before the next scan */
 		while (timeout && !kthread_should_stop())
-- 
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