From e6c352dbc0f4dc7e3f82feafb9e6207c5814a189 Mon Sep 17 00:00:00 2001 From: Joel Becker Date: Sat, 3 Feb 2007 03:04:20 -0800 Subject: [PATCH] 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 Signed-off-by: Mark Fasheh --- fs/ocfs2/cluster/heartbeat.c | 44 ++++++++++++++++++++++++++---------- 1 file 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(®->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(®->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); } -- 2.20.1