From: Faisal Latif <faisal.latif@intel.com>
Date: Sat, 22 Nov 2008 02:50:55 +0000 (-0600)
Subject: RDMA/nes: Check cqp_avail_reqs is empty after locking the list
X-Git-Tag: v2.6.29-rc1~583^2^6~3
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=f3181a10e13ac55e18958d7c48cba6f925c71483;p=linux-2.6-omap-h63xx.git

RDMA/nes: Check cqp_avail_reqs is empty after locking the list

Between the first empty list check and locking the list, the list can
change.  Check it again after it is locked to make sure the list is
still not empty.

Signed-off-by: Faisal Latif <faisal.latif@intel.com>
Signed-off-by: Chien Tung <chien.tin.tung@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
---

diff --git a/drivers/infiniband/hw/nes/nes_utils.c b/drivers/infiniband/hw/nes/nes_utils.c
index fb8cbd71a2e..5611a73d583 100644
--- a/drivers/infiniband/hw/nes/nes_utils.c
+++ b/drivers/infiniband/hw/nes/nes_utils.c
@@ -540,11 +540,14 @@ struct nes_cqp_request *nes_get_cqp_request(struct nes_device *nesdev)
 
 	if (!list_empty(&nesdev->cqp_avail_reqs)) {
 		spin_lock_irqsave(&nesdev->cqp.lock, flags);
-		cqp_request = list_entry(nesdev->cqp_avail_reqs.next,
+		if (!list_empty(&nesdev->cqp_avail_reqs)) {
+			cqp_request = list_entry(nesdev->cqp_avail_reqs.next,
 				struct nes_cqp_request, list);
-		list_del_init(&cqp_request->list);
+			list_del_init(&cqp_request->list);
+		}
 		spin_unlock_irqrestore(&nesdev->cqp.lock, flags);
-	} else {
+	}
+	if (cqp_request == NULL) {
 		cqp_request = kzalloc(sizeof(struct nes_cqp_request), GFP_KERNEL);
 		if (cqp_request) {
 			cqp_request->dynamic = 1;