From 6f8648e894498f769832b79399b1cfabd2973ea9 Mon Sep 17 00:00:00 2001 From: Joyce Date: Wed, 11 Sep 2013 14:20:03 -0700 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 Signed-off-by: Joseph Qi Cc: Joel Becker Cc: Mark Fasheh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ocfs2/cluster/heartbeat.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'fs') 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); -- cgit v1.2.3-59-g8ed1b