If ceph_fault() is unable to queue work after a delay, it sets the
BACKOFF connection flag so con_work() will attempt to do so.
In con_work(), when BACKOFF is set, if queue_delayed_work() doesn't
result in newly-queued work, it simply ignores this condition and
proceeds as if no backoff delay were desired. There are two
problems with this--one of which is a bug.
The first problem is simply that the intended behavior is to back
off, and if we aren't able queue the work item to run after a delay
we're not doing that.
The only reason queue_delayed_work() won't queue work is if the
provided work item is already queued. In the messenger, this
means that con_work() is already scheduled to be run again. So
if we simply set the BACKOFF flag again when this occurs, we know
the next con_work() call will again attempt to hold off activity
on the connection until after the delay.
The second problem--the bug--is a leak of a reference count. If
queue_delayed_work() returns 0 in con_work(), con->ops->put() drops
the connection reference held on entry to con_work(). However,
processing is (was) allowed to continue, and at the end of the
function a second con->ops->put() is called.
This patch fixes both problems.
Signed-off-by: Alex Elder <elder@xxxxxxxxxxx>
---
net/ceph/messenger.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index f9f65fe..ece06bc 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -2300,10 +2300,11 @@ restart:
mutex_unlock(&con->mutex);
return;
} else {
- con->ops->put(con);
dout("con_work %p FAILED to back off %lu\n", con,
con->delay);
+ set_bit(CON_FLAG_BACKOFF, &con->flags);
}
+ goto done;
}
if (con->state == CON_STATE_STANDBY) {
--
1.7.9.5
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