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kmemleak: Do not trigger a scan when reading the debug/kmemleak file

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Since there is a kernel thread for automatically scanning the memory, it
makes sense for the debug/kmemleak file to only show its findings. This
patch also adds support for "echo scan > debug/kmemleak" to trigger an
intermediate memory scan and eliminates the kmemleak_mutex (scan_mutex
covers all the cases now).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas
2009-06-26 17:38:27 +01:00
parent bab4a34afc
commit 4698c1f2bb
2 changed files with 48 additions and 53 deletions
Download Patch File Download Diff File Expand all files Collapse all files
mm/kmemleak.c
+41 -51
View File
@@ -48,10 +48,10 @@
* scanned. This list is only modified during a scanning episode when the
* scan_mutex is held. At the end of a scan, the gray_list is always empty.
* Note that the kmemleak_object.use_count is incremented when an object is
* added to the gray_list and therefore cannot be freed
* - kmemleak_mutex (mutex): prevents multiple users of the "kmemleak" debugfs
* file together with modifications to the memory scanning parameters
* including the scan_thread pointer
* added to the gray_list and therefore cannot be freed. This mutex also
* prevents multiple users of the "kmemleak" debugfs file together with
* modifications to the memory scanning parameters including the scan_thread
* pointer
*
* The kmemleak_object structures have a use_count incremented or decremented
* using the get_object()/put_object() functions. When the use_count becomes
@@ -195,10 +195,8 @@ static unsigned long jiffies_min_age;
static signed long jiffies_scan_wait;
/* enables or disables the task stacks scanning */
static int kmemleak_stack_scan = 1;
/* mutex protecting the memory scanning */
/* protects the memory scanning, parameters and debug/kmemleak file access */
static DEFINE_MUTEX(scan_mutex);
/* mutex protecting the access to the /sys/kernel/debug/kmemleak file */
static DEFINE_MUTEX(kmemleak_mutex);
/* number of leaks reported (for limitation purposes) */
static int reported_leaks;
@@ -927,6 +925,7 @@ static void kmemleak_scan(void)
struct kmemleak_object *object, *tmp;
struct task_struct *task;
int i;
int new_leaks = 0;
/* prepare the kmemleak_object's */
rcu_read_lock();
@@ -1024,6 +1023,26 @@ static void kmemleak_scan(void)
object = tmp;
}
WARN_ON(!list_empty(&gray_list));
/*
* Scanning result reporting.
*/
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
spin_lock_irqsave(&object->lock, flags);
if (unreferenced_object(object) &&
!(object->flags & OBJECT_REPORTED)) {
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);
}
/*
@@ -1045,33 +1064,12 @@ 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();
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
unsigned long flags;
spin_lock_irqsave(&object->lock, flags);
if (unreferenced_object(object) &&
!(object->flags & OBJECT_REPORTED)) {
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())
timeout = schedule_timeout_interruptible(timeout);
@@ -1084,7 +1082,7 @@ static int kmemleak_scan_thread(void *arg)
/*
* Start the automatic memory scanning thread. This function must be called
* with the kmemleak_mutex held.
* with the scan_mutex held.
*/
void start_scan_thread(void)
{
@@ -1099,7 +1097,7 @@ void start_scan_thread(void)
/*
* Stop the automatic memory scanning thread. This function must be called
* with the kmemleak_mutex held.
* with the scan_mutex held.
*/
void stop_scan_thread(void)
{
@@ -1119,10 +1117,8 @@ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
struct kmemleak_object *object;
loff_t n = *pos;
if (!n) {
kmemleak_scan();
if (!n)
reported_leaks = 0;
}
if (reported_leaks >= REPORTS_NR)
return NULL;
@@ -1206,13 +1202,10 @@ static int kmemleak_open(struct inode *inode, struct file *file)
if (!atomic_read(&kmemleak_enabled))
return -EBUSY;
ret = mutex_lock_interruptible(&kmemleak_mutex);
ret = mutex_lock_interruptible(&scan_mutex);
if (ret < 0)
goto out;
if (file->f_mode & FMODE_READ) {
ret = mutex_lock_interruptible(&scan_mutex);
if (ret < 0)
goto kmemleak_unlock;
ret = seq_open(file, &kmemleak_seq_ops);
if (ret < 0)
goto scan_unlock;
@@ -1221,8 +1214,6 @@ static int kmemleak_open(struct inode *inode, struct file *file)
scan_unlock:
mutex_unlock(&scan_mutex);
kmemleak_unlock:
mutex_unlock(&kmemleak_mutex);
out:
return ret;
}
@@ -1231,11 +1222,9 @@ static int kmemleak_release(struct inode *inode, struct file *file)
{
int ret = 0;
if (file->f_mode & FMODE_READ) {
if (file->f_mode & FMODE_READ)
seq_release(inode, file);
mutex_unlock(&scan_mutex);
}
mutex_unlock(&kmemleak_mutex);
mutex_unlock(&scan_mutex);
return ret;
}
@@ -1250,6 +1239,7 @@ static int kmemleak_release(struct inode *inode, struct file *file)
* scan=off - stop the automatic memory scanning thread
* scan=... - set the automatic memory scanning period in seconds (0 to
* disable it)
* scan - trigger a memory scan
*/
static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
size_t size, loff_t *ppos)
@@ -1287,7 +1277,9 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
start_scan_thread();
}
} else
} else if (strncmp(buf, "scan", 4) == 0)
kmemleak_scan();
else
return -EINVAL;
/* ignore the rest of the buffer, only one command at a time */
@@ -1312,11 +1304,9 @@ static int kmemleak_cleanup_thread(void *arg)
{
struct kmemleak_object *object;
mutex_lock(&kmemleak_mutex);
stop_scan_thread();
mutex_unlock(&kmemleak_mutex);
mutex_lock(&scan_mutex);
stop_scan_thread();
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object(object->pointer);
@@ -1458,9 +1448,9 @@ static int __init kmemleak_late_init(void)
&kmemleak_fops);
if (!dentry)
pr_warning("Failed to create the debugfs kmemleak file\n");
mutex_lock(&kmemleak_mutex);
mutex_lock(&scan_mutex);
start_scan_thread();
mutex_unlock(&kmemleak_mutex);
mutex_unlock(&scan_mutex);
pr_info("Kernel memory leak detector initialized\n");