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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>
hifive-unleashed-5.1
Joyce 2013-09-11 14:20:03 -07:00 committed by Linus Torvalds
parent 03dbe88aa9
commit 6f8648e894
1 changed files with 9 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
fs/ocfs2/cluster/heartbeat.c
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@ -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);