IB/hfi1: Fix the count of user packets submitted to an SDMA engine

Each user SDMA request coming into the driver may contain multiple packets.
Each user packet may use multiple SDMA descriptors to fill the send buffer.
The field seqsubmitted in struct user_sdma_request counts the number of
user packets submitted to an SDMA engine. Sometimes, the intermediate count
may not be updated properly. However, once all the packets' descriptors
are successfully submitted to the SDMA engine, the final count is updated
correctly. But, if only some of the packets are submitted to the engine due
to an error, the intermediate count doesn't reflect the partial number of
packets submitted to the SDMA engine. This can cause a hang later in the
code as the count of packets submitted to the SDMA engine doesn't match the
the count of packets processed by the SDMA engine.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 13 insertions, 18 deletions

diff --git a/drivers/infiniband/hw/hfi1/user_sdma.c b/drivers/infiniband/hw/hfi1/user_sdma.c
index 1694037d1eee..bc7e5c179f80 100644
--- a/drivers/infiniband/hw/hfi1/user_sdma.c
+++ b/drivers/infiniband/hw/hfi1/user_sdma.c
@@ -894,7 +894,7 @@ static inline u32 get_lrh_len(struct hfi1_pkt_header hdr, u32 len)
 
 static int user_sdma_send_pkts(struct user_sdma_request *req, unsigned maxpkts)
 {
-	int ret = 0;
+	int ret = 0, count;
 	unsigned npkts = 0;
 	struct user_sdma_txreq *tx = NULL;
 	struct hfi1_user_sdma_pkt_q *pq = NULL;
@@ -1090,23 +1090,18 @@ static int user_sdma_send_pkts(struct user_sdma_request *req, unsigned maxpkts)
 		npkts++;
 	}
 dosend:
-	ret = sdma_send_txlist(req->sde, &pq->busy, &req->txps);
-	if (list_empty(&req->txps)) {
-		req->seqsubmitted = req->seqnum;
-		if (req->seqnum == req->info.npkts) {
-			set_bit(SDMA_REQ_SEND_DONE, &req->flags);
-			/*
-			 * The txreq has already been submitted to the HW queue
-			 * so we can free the AHG entry now. Corruption will not
-			 * happen due to the sequential manner in which
-			 * descriptors are processed.
-			 */
-			if (test_bit(SDMA_REQ_HAVE_AHG, &req->flags))
-				sdma_ahg_free(req->sde, req->ahg_idx);
-		}
-	} else if (ret > 0) {
-		req->seqsubmitted += ret;
-		ret = 0;
+	ret = sdma_send_txlist(req->sde, &pq->busy, &req->txps, &count);
+	req->seqsubmitted += count;
+	if (req->seqsubmitted == req->info.npkts) {
+		set_bit(SDMA_REQ_SEND_DONE, &req->flags);
+		/*
+		 * The txreq has already been submitted to the HW queue
+		 * so we can free the AHG entry now. Corruption will not
+		 * happen due to the sequential manner in which
+		 * descriptors are processed.
+		 */
+		if (test_bit(SDMA_REQ_HAVE_AHG, &req->flags))
+			sdma_ahg_free(req->sde, req->ahg_idx);
 	}
 	return ret;