lkml.org 
[lkml]   [2006]   [Jul]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] mthca: initialize send and receive queue locks separately
Date
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: Zach Brown <zach.brown@oracle.com>
---
drivers/infiniband/hw/mthca/mthca_qp.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
Index: 2.6.17-mm6/drivers/infiniband/hw/mthca/mthca_qp.c
===================================================================
--- 2.6.17-mm6.orig/drivers/infiniband/hw/mthca/mthca_qp.c 2006-07-03 08:41:16.000000000 -0400
+++ 2.6.17-mm6/drivers/infiniband/hw/mthca/mthca_qp.c 2006-07-03 10:05:52.000000000 -0400
@@ -224,7 +224,7 @@

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 @@
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)
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2006-07-04 00:52    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site