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authorJoel Becker <joel.becker@oracle.com>2007-02-03 03:04:20 -0800
committerMark Fasheh <mark.fasheh@oracle.com>2007-03-14 14:37:12 -0700
commite6c352dbc0f4dc7e3f82feafb9e6207c5814a189 (patch)
tree796049268fa7a90ee87f2f01a109354f7a54ce01
parentc24f72cc7ca829bbad0532ddf315ace3ae1c359e (diff)
ocfs2: Concurrent access of o2hb_region->hr_task was not locked
This means that a build-up and a teardown could race which would result in a double-kthread_stop(). Protect the setting and clearing of hr_task with o2hb_live_lock, as it's not a common thing and not performance critical. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
-rw-r--r--fs/ocfs2/cluster/heartbeat.c44
1 files changed, 32 insertions, 12 deletions
diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 0f2cfecd42c..eba282da500 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -1234,6 +1234,7 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
const char *page,
size_t count)
{
+ struct task_struct *hb_task;
long fd;
int sectsize;
char *p = (char *)page;
@@ -1319,20 +1320,28 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
*/
atomic_set(&reg->hr_steady_iterations, O2HB_LIVE_THRESHOLD + 1);
- reg->hr_task = kthread_run(o2hb_thread, reg, "o2hb-%s",
- reg->hr_item.ci_name);
- if (IS_ERR(reg->hr_task)) {
- ret = PTR_ERR(reg->hr_task);
+ hb_task = kthread_run(o2hb_thread, reg, "o2hb-%s",
+ reg->hr_item.ci_name);
+ if (IS_ERR(hb_task)) {
+ ret = PTR_ERR(hb_task);
mlog_errno(ret);
- reg->hr_task = NULL;
goto out;
}
+ spin_lock(&o2hb_live_lock);
+ reg->hr_task = hb_task;
+ spin_unlock(&o2hb_live_lock);
+
ret = wait_event_interruptible(o2hb_steady_queue,
atomic_read(&reg->hr_steady_iterations) == 0);
if (ret) {
- kthread_stop(reg->hr_task);
+ spin_lock(&o2hb_live_lock);
+ hb_task = reg->hr_task;
reg->hr_task = NULL;
+ spin_unlock(&o2hb_live_lock);
+
+ if (hb_task)
+ kthread_stop(hb_task);
goto out;
}
@@ -1354,10 +1363,17 @@ out:
static ssize_t o2hb_region_pid_read(struct o2hb_region *reg,
char *page)
{
- if (!reg->hr_task)
+ pid_t pid = 0;
+
+ spin_lock(&o2hb_live_lock);
+ if (reg->hr_task)
+ pid = reg->hr_task->pid;
+ spin_unlock(&o2hb_live_lock);
+
+ if (!pid)
return 0;
- return sprintf(page, "%u\n", reg->hr_task->pid);
+ return sprintf(page, "%u\n", pid);
}
struct o2hb_region_attribute {
@@ -1495,13 +1511,17 @@ out:
static void o2hb_heartbeat_group_drop_item(struct config_group *group,
struct config_item *item)
{
+ struct task_struct *hb_task;
struct o2hb_region *reg = to_o2hb_region(item);
/* stop the thread when the user removes the region dir */
- if (reg->hr_task) {
- kthread_stop(reg->hr_task);
- reg->hr_task = NULL;
- }
+ spin_lock(&o2hb_live_lock);
+ hb_task = reg->hr_task;
+ reg->hr_task = NULL;
+ spin_unlock(&o2hb_live_lock);
+
+ if (hb_task)
+ kthread_stop(hb_task);
config_item_put(item);
}