IB/mthca: Make all device methods truly reentrant

Documentation/infiniband/core_locking.txt says:

  All of the methods in struct ib_device exported by a low-level
  driver must be fully reentrant.  The low-level driver is required to
  perform all synchronization necessary to maintain consistency, even
  if multiple function calls using the same object are run
  simultaneously.

However, mthca's modify_qp, modify_srq and resize_cq methods are
currently not reentrant.  Add a mutex to the QP, SRQ and CQ structures
so that these calls can be properly serialized.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 16 insertions, 7 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c
index 8f89ba7c9147..230ae21db8fd 100644
--- a/drivers/infiniband/hw/mthca/mthca_provider.c
+++ b/drivers/infiniband/hw/mthca/mthca_provider.c
@@ -793,18 +793,24 @@ static int mthca_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *uda
 	if (entries < 1 || entries > dev->limits.max_cqes)
 		return -EINVAL;
 
+	mutex_lock(&cq->mutex);
+
 	entries = roundup_pow_of_two(entries + 1);
-	if (entries == ibcq->cqe + 1)
-		return 0;
+	if (entries == ibcq->cqe + 1) {
+		ret = 0;
+		goto out;
+	}
 
 	if (cq->is_kernel) {
 		ret = mthca_alloc_resize_buf(dev, cq, entries);
 		if (ret)
-			return ret;
+			goto out;
 		lkey = cq->resize_buf->buf.mr.ibmr.lkey;
 	} else {
-		if (ib_copy_from_udata(&ucmd, udata, sizeof ucmd))
-			return -EFAULT;
+		if (ib_copy_from_udata(&ucmd, udata, sizeof ucmd)) {
+			ret = -EFAULT;
+			goto out;
+		}
 		lkey = ucmd.lkey;
 	}
 
@@ -821,7 +827,7 @@ static int mthca_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *uda
 			cq->resize_buf = NULL;
 			spin_unlock_irq(&cq->lock);
 		}
-		return ret;
+		goto out;
 	}
 
 	if (cq->is_kernel) {
@@ -848,7 +854,10 @@ static int mthca_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *uda
 	} else
 		ibcq->cqe = entries - 1;
 
-	return 0;
+out:
+	mutex_unlock(&cq->mutex);
+
+	return ret;
 }
 
 static int mthca_destroy_cq(struct ib_cq *cq)