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authorJoyce <xuejiufei@huawei.com>2013-09-11 14:20:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:56:51 -0700
commit6f8648e894498f769832b79399b1cfabd2973ea9 (patch)
tree4ea339363940a3412d8be1dfe668f66eda03214f /fs/ocfs2
parent03dbe88aa9cd0d7b0a876b38bd75ce73b4522454 (diff)
ocfs2: fix a tiny race case when firing callbacks
In o2hb_shutdown_slot() and o2hb_check_slot(), since event is defined as local, it is only valid during the call stack. So the following tiny race case may happen in a multi-volumes mounted environment: o2hb-vol1 o2hb-vol2 1) o2hb_shutdown_slot allocate local event1 2) queue_node_event add event1 to global o2hb_node_events 3) o2hb_shutdown_slot allocate local event2 4) queue_node_event add event2 to global o2hb_node_events 5) o2hb_run_event_list delete event1 from o2hb_node_events 6) o2hb_run_event_list event1 empty, return 7) o2hb_shutdown_slot event1 lifecycle ends 8) o2hb_fire_callbacks event1 is already *invalid* This patch lets it wait on o2hb_callback_sem when another thread is firing callbacks. And for performance consideration, we only call o2hb_run_event_list when there is an event queued. Signed-off-by: Joyce <xuejiufei@huawei.com> Signed-off-by: Joseph Qi <joseph.qi@huawei.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ocfs2')
-rw-r--r--fs/ocfs2/cluster/heartbeat.c18
1 files changed, 9 insertions, 9 deletions
diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 25b72e82b8fa..363f0dcc924f 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -639,16 +639,9 @@ static void o2hb_fire_callbacks(struct o2hb_callback *hbcall,
/* Will run the list in order until we process the passed event */
static void o2hb_run_event_list(struct o2hb_node_event *queued_event)
{
- int empty;
struct o2hb_callback *hbcall;
struct o2hb_node_event *event;
- spin_lock(&o2hb_live_lock);
- empty = list_empty(&queued_event->hn_item);
- spin_unlock(&o2hb_live_lock);
- if (empty)
- return;
-
/* Holding callback sem assures we don't alter the callback
* lists when doing this, and serializes ourselves with other
* processes wanting callbacks. */
@@ -707,6 +700,7 @@ static void o2hb_shutdown_slot(struct o2hb_disk_slot *slot)
struct o2hb_node_event event =
{ .hn_item = LIST_HEAD_INIT(event.hn_item), };
struct o2nm_node *node;
+ int queued = 0;
node = o2nm_get_node_by_num(slot->ds_node_num);
if (!node)
@@ -724,11 +718,13 @@ static void o2hb_shutdown_slot(struct o2hb_disk_slot *slot)
o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB, node,
slot->ds_node_num);
+ queued = 1;
}
}
spin_unlock(&o2hb_live_lock);
- o2hb_run_event_list(&event);
+ if (queued)
+ o2hb_run_event_list(&event);
o2nm_node_put(node);
}
@@ -788,6 +784,7 @@ static int o2hb_check_slot(struct o2hb_region *reg,
unsigned int dead_ms = o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS;
unsigned int slot_dead_ms;
int tmp;
+ int queued = 0;
memcpy(hb_block, slot->ds_raw_block, reg->hr_block_bytes);
@@ -881,6 +878,7 @@ fire_callbacks:
slot->ds_node_num);
changed = 1;
+ queued = 1;
}
list_add_tail(&slot->ds_live_item,
@@ -932,6 +930,7 @@ fire_callbacks:
node, slot->ds_node_num);
changed = 1;
+ queued = 1;
}
/* We don't clear this because the node is still
@@ -947,7 +946,8 @@ fire_callbacks:
out:
spin_unlock(&o2hb_live_lock);
- o2hb_run_event_list(&event);
+ if (queued)
+ o2hb_run_event_list(&event);
if (node)
o2nm_node_put(node);