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>
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@ -1234,6 +1234,7 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
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const char *page,
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size_t count)
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{
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struct task_struct *hb_task;
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long fd;
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int sectsize;
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char *p = (char *)page;
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@ -1319,20 +1320,28 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
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*/
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atomic_set(®->hr_steady_iterations, O2HB_LIVE_THRESHOLD + 1);
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reg->hr_task = kthread_run(o2hb_thread, reg, "o2hb-%s",
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reg->hr_item.ci_name);
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if (IS_ERR(reg->hr_task)) {
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ret = PTR_ERR(reg->hr_task);
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hb_task = kthread_run(o2hb_thread, reg, "o2hb-%s",
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reg->hr_item.ci_name);
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if (IS_ERR(hb_task)) {
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ret = PTR_ERR(hb_task);
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mlog_errno(ret);
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reg->hr_task = NULL;
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goto out;
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}
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spin_lock(&o2hb_live_lock);
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reg->hr_task = hb_task;
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spin_unlock(&o2hb_live_lock);
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ret = wait_event_interruptible(o2hb_steady_queue,
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atomic_read(®->hr_steady_iterations) == 0);
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if (ret) {
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kthread_stop(reg->hr_task);
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spin_lock(&o2hb_live_lock);
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hb_task = reg->hr_task;
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reg->hr_task = NULL;
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spin_unlock(&o2hb_live_lock);
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if (hb_task)
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kthread_stop(hb_task);
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goto out;
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}
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@ -1354,10 +1363,17 @@ out:
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static ssize_t o2hb_region_pid_read(struct o2hb_region *reg,
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char *page)
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{
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if (!reg->hr_task)
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pid_t pid = 0;
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spin_lock(&o2hb_live_lock);
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if (reg->hr_task)
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pid = reg->hr_task->pid;
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spin_unlock(&o2hb_live_lock);
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if (!pid)
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return 0;
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return sprintf(page, "%u\n", reg->hr_task->pid);
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return sprintf(page, "%u\n", pid);
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}
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struct o2hb_region_attribute {
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@ -1495,13 +1511,17 @@ out:
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static void o2hb_heartbeat_group_drop_item(struct config_group *group,
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struct config_item *item)
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{
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struct task_struct *hb_task;
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struct o2hb_region *reg = to_o2hb_region(item);
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/* stop the thread when the user removes the region dir */
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if (reg->hr_task) {
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kthread_stop(reg->hr_task);
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reg->hr_task = NULL;
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}
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spin_lock(&o2hb_live_lock);
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hb_task = reg->hr_task;
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reg->hr_task = NULL;
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spin_unlock(&o2hb_live_lock);
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if (hb_task)
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kthread_stop(hb_task);
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config_item_put(item);
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}
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