Commit a46f9484 authored by Zach Brown's avatar Zach Brown Committed by Linus Torvalds
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[PATCH] mthca: initialize send and receive queue locks separately



mthca: initialize send and receive queue locks separately

lockdep identifies a lock by the call site of its initialization.  By
initializing the send and receive queue locks in mthca_wq_init() we confuse
lockdep.  It warns that that the ordered acquiry of both locks in
mthca_modify_qp() is recursive acquiry of one lock:

  =============================================
  [ INFO: possible recursive locking detected ]
  ---------------------------------------------
  modprobe/1192 is trying to acquire lock:
   (&wq->lock){....}, at: [<f892b4db>] mthca_modify_qp+0x60/0xa7b [ib_mthca]
  but task is already holding lock:
   (&wq->lock){....}, at: [<f892b4ce>] mthca_modify_qp+0x53/0xa7b [ib_mthca]

Initializing the locks separately in mthca_alloc_qp_common() stops the
warning and will let lockdep enforce proper ordering on paths that acquire
both locks.
Signed-off-by: default avatarZach Brown <zach.brown@oracle.com>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent dd8041f1
......@@ -224,7 +224,7 @@ static void *get_send_wqe(struct mthca_qp *qp, int n)
static void mthca_wq_init(struct mthca_wq *wq)
{
spin_lock_init(&wq->lock);
/* mthca_alloc_qp_common() initializes the locks */
wq->next_ind = 0;
wq->last_comp = wq->max - 1;
wq->head = 0;
......@@ -1114,6 +1114,9 @@ static int mthca_alloc_qp_common(struct mthca_dev *dev,
qp->sq_policy = send_policy;
mthca_wq_init(&qp->sq);
mthca_wq_init(&qp->rq);
/* these are initialized separately so lockdep can tell them apart */
spin_lock_init(&qp->sq.lock);
spin_lock_init(&qp->rq.lock);
ret = mthca_map_memfree(dev, qp);
if (ret)
......
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