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libceph: recheck con state after allocating incoming message

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We drop the lock when calling the ->alloc_msg() con op, which means
we need to (a) not clobber con->in_msg without the mutex held, and (b)
we need to verify that we are still in the OPEN state when we retake
it to avoid causing any mayhem.  If the state does change, -EAGAIN
will get us back to con_work() and loop.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
This commit is contained in:
Sage Weil 2012-07-30 18:19:45 -07:00
parent 4740a623d2
commit 6139919133
1 changed files with 8 additions and 1 deletions
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9
net/ceph/messenger.c
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@ -2735,9 +2735,16 @@ static int ceph_con_in_msg_alloc(struct ceph_connection *con, int *skip)
BUG_ON(con->in_msg != NULL);
if (con->ops->alloc_msg) {
struct ceph_msg *msg;
mutex_unlock(&con->mutex);
con->in_msg = con->ops->alloc_msg(con, hdr, skip);
msg = con->ops->alloc_msg(con, hdr, skip);
mutex_lock(&con->mutex);
if (con->state != CON_STATE_OPEN) {
ceph_msg_put(msg);
return -EAGAIN;
}
con->in_msg = msg;
if (con->in_msg) {
con->in_msg->con = con->ops->get(con);
BUG_ON(con->in_msg->con == NULL);