Subject: [merged] ocfs2-fix-a-tiny-race-case-when-firing-callbacks.patch removed from -mm tree
To: xuejiufei@xxxxxxxxxx,jlbec@xxxxxxxxxxxx,joseph.qi@xxxxxxxxxx,mfasheh@xxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 12 Sep 2013 12:41:51 -0700
The patch titled
Subject: ocfs2: fix a tiny race case when firing callbacks
has been removed from the -mm tree. Its filename was
ocfs2-fix-a-tiny-race-case-when-firing-callbacks.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Joyce <xuejiufei@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Signed-off-by: Joseph Qi <joseph.qi@xxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/cluster/heartbeat.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff -puN fs/ocfs2/cluster/heartbeat.c~ocfs2-fix-a-tiny-race-case-when-firing-callbacks fs/ocfs2/cluster/heartbeat.c
--- a/fs/ocfs2/cluster/heartbeat.c~ocfs2-fix-a-tiny-race-case-when-firing-callbacks
+++ a/fs/ocfs2/cluster/heartbeat.c
@@ -639,16 +639,9 @@ static void o2hb_fire_callbacks(struct o
/* 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 o2
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 o2
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_r
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);
_
Patches currently in -mm which might be from xuejiufei@xxxxxxxxxx are
origin.patch
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