[IB] Fix MAD layer DMA mappings to avoid touching data buffer once mapped

The MAD layer was violating the DMA API by touching data buffers used
for sends after the DMA mapping was done.  This causes problems on
non-cache-coherent architectures, because the device doing DMA won't
see updates to the payload buffers that exist only in the CPU cache.

Fix this by having all MAD consumers use ib_create_send_mad() to
allocate their send buffers, and moving the DMA mapping into the MAD
layer so it can be done just before calling send (and after any
modifications of the send buffer by the MAD layer).

Tested on a non-cache-coherent PowerPC 440SPe system.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 21 insertions, 26 deletions

diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index fd200c064a2e..fc5519a3de99 100644
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -96,7 +96,6 @@ struct ib_umad_file {
 };
 
 struct ib_umad_packet {
-	struct ib_ah      *ah;
 	struct ib_mad_send_buf *msg;
 	struct list_head   list;
 	int		   length;
@@ -139,10 +138,10 @@ static void send_handler(struct ib_mad_agent *agent,
 			 struct ib_mad_send_wc *send_wc)
 {
 	struct ib_umad_file *file = agent->context;
-	struct ib_umad_packet *timeout, *packet =
-		(void *) (unsigned long) send_wc->wr_id;
+	struct ib_umad_packet *timeout;
+	struct ib_umad_packet *packet = send_wc->send_buf->context[0];
 
-	ib_destroy_ah(packet->msg->send_wr.wr.ud.ah);
+	ib_destroy_ah(packet->msg->ah);
 	ib_free_send_mad(packet->msg);
 
 	if (send_wc->status == IB_WC_RESP_TIMEOUT_ERR) {
@@ -268,11 +267,11 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
 	struct ib_umad_packet *packet;
 	struct ib_mad_agent *agent;
 	struct ib_ah_attr ah_attr;
-	struct ib_send_wr *bad_wr;
+	struct ib_ah *ah;
 	struct ib_rmpp_mad *rmpp_mad;
 	u8 method;
 	__be64 *tid;
-	int ret, length, hdr_len, data_len, rmpp_hdr_size;
+	int ret, length, hdr_len, rmpp_hdr_size;
 	int rmpp_active = 0;
 
 	if (count < sizeof (struct ib_user_mad))
@@ -321,9 +320,9 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
 		ah_attr.grh.traffic_class  = packet->mad.hdr.traffic_class;
 	}
 
-	packet->ah = ib_create_ah(agent->qp->pd, &ah_attr);
-	if (IS_ERR(packet->ah)) {
-		ret = PTR_ERR(packet->ah);
+	ah = ib_create_ah(agent->qp->pd, &ah_attr);
+	if (IS_ERR(ah)) {
+		ret = PTR_ERR(ah);
 		goto err_up;
 	}
 
@@ -337,12 +336,10 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
 
 		/* Validate that the management class can support RMPP */
 		if (rmpp_mad->mad_hdr.mgmt_class == IB_MGMT_CLASS_SUBN_ADM) {
-			hdr_len = offsetof(struct ib_sa_mad, data);
-			data_len = length - hdr_len;
+			hdr_len = IB_MGMT_SA_HDR;
 		} else if ((rmpp_mad->mad_hdr.mgmt_class >= IB_MGMT_CLASS_VENDOR_RANGE2_START) &&
 			    (rmpp_mad->mad_hdr.mgmt_class <= IB_MGMT_CLASS_VENDOR_RANGE2_END)) {
-				hdr_len = offsetof(struct ib_vendor_mad, data);
-				data_len = length - hdr_len;
+				hdr_len = IB_MGMT_VENDOR_HDR;
 		} else {
 			ret = -EINVAL;
 			goto err_ah;
@@ -353,25 +350,23 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
 			ret = -EINVAL;
 			goto err_ah;
 		}
-		hdr_len = offsetof(struct ib_mad, data);
-		data_len = length - hdr_len;
+		hdr_len = IB_MGMT_MAD_HDR;
 	}
 
 	packet->msg = ib_create_send_mad(agent,
 					 be32_to_cpu(packet->mad.hdr.qpn),
-					 0, packet->ah, rmpp_active,
-					 hdr_len, data_len,
+					 0, rmpp_active,
+					 hdr_len, length - hdr_len,
 					 GFP_KERNEL);
 	if (IS_ERR(packet->msg)) {
 		ret = PTR_ERR(packet->msg);
 		goto err_ah;
 	}
 
-	packet->msg->send_wr.wr.ud.timeout_ms  = packet->mad.hdr.timeout_ms;
-	packet->msg->send_wr.wr.ud.retries = packet->mad.hdr.retries;
-
-	/* Override send WR WRID initialized in ib_create_send_mad */
-	packet->msg->send_wr.wr_id = (unsigned long) packet;
+	packet->msg->ah 	= ah;
+	packet->msg->timeout_ms = packet->mad.hdr.timeout_ms;
+	packet->msg->retries 	= packet->mad.hdr.retries;
+	packet->msg->context[0] = packet;
 
 	if (!rmpp_active) {
 		/* Copy message from user into send buffer */
@@ -403,17 +398,17 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
 	 * transaction ID matches the agent being used to send the
 	 * MAD.
 	 */
-	method = packet->msg->mad->mad_hdr.method;
+	method = ((struct ib_mad_hdr *) packet->msg)->method;
 
 	if (!(method & IB_MGMT_METHOD_RESP)       &&
 	    method != IB_MGMT_METHOD_TRAP_REPRESS &&
 	    method != IB_MGMT_METHOD_SEND) {
-		tid = &packet->msg->mad->mad_hdr.tid;
+		tid = &((struct ib_mad_hdr *) packet->msg)->tid;
 		*tid = cpu_to_be64(((u64) agent->hi_tid) << 32 |
 				   (be64_to_cpup(tid) & 0xffffffff));
 	}
 
-	ret = ib_post_send_mad(agent, &packet->msg->send_wr, &bad_wr);
+	ret = ib_post_send_mad(packet->msg, NULL);
 	if (ret)
 		goto err_msg;
 
@@ -425,7 +420,7 @@ err_msg:
 	ib_free_send_mad(packet->msg);
 
 err_ah:
-	ib_destroy_ah(packet->ah);
+	ib_destroy_ah(ah);
 
 err_up:
 	up_read(&file->agent_mutex);