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ocfs2: Concurrent access of o2hb_region->hr_task was not locked

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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>
This commit is contained in:
Joel Becker 2007-02-03 03:04:20 -08:00 committed by Mark Fasheh
parent c24f72cc7c
commit e6c352dbc0
1 changed files with 32 additions and 12 deletions
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44
fs/ocfs2/cluster/heartbeat.c
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@ -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);
}