IB/qib: Fix a possible data corruption when receiving packets

Prevent a receive data corruption by ensuring that the write to update
the rcvhdrheadn register to generate an interrupt is at the very end
of the receive processing.

Signed-off-by: Ramkrishna Vepa <ram.vepa@qlogic.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Cc: <stable@kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/qib/qib_iba6120.c

@@ -2076,9 +2076,11 @@ static void qib_6120_config_ctxts(struct qib_devdata *dd)
 static void qib_update_6120_usrhead(struct qib_ctxtdata *rcd, u64 hd,
 				    u32 updegr, u32 egrhd, u32 npkts)
 {
-	qib_write_ureg(rcd->dd, ur_rcvhdrhead, hd, rcd->ctxt);
 	if (updegr)
 		qib_write_ureg(rcd->dd, ur_rcvegrindexhead, egrhd, rcd->ctxt);
+	mmiowb();
+	qib_write_ureg(rcd->dd, ur_rcvhdrhead, hd, rcd->ctxt);
+	mmiowb();
 }
 
 static u32 qib_6120_hdrqempty(struct qib_ctxtdata *rcd)

drivers/infiniband/hw/qib/qib_iba7220.c

@@ -2725,9 +2725,11 @@ static int qib_7220_set_loopback(struct qib_pportdata *ppd, const char *what)
 static void qib_update_7220_usrhead(struct qib_ctxtdata *rcd, u64 hd,
 				    u32 updegr, u32 egrhd, u32 npkts)
 {
-	qib_write_ureg(rcd->dd, ur_rcvhdrhead, hd, rcd->ctxt);
 	if (updegr)
 		qib_write_ureg(rcd->dd, ur_rcvegrindexhead, egrhd, rcd->ctxt);
+	mmiowb();
+	qib_write_ureg(rcd->dd, ur_rcvhdrhead, hd, rcd->ctxt);
+	mmiowb();
 }
 
 static u32 qib_7220_hdrqempty(struct qib_ctxtdata *rcd)

drivers/infiniband/hw/qib/qib_iba7322.c

@@ -4083,10 +4083,12 @@ static void qib_update_7322_usrhead(struct qib_ctxtdata *rcd, u64 hd,
 	 */
 	if (hd >> IBA7322_HDRHEAD_PKTINT_SHIFT)
 		adjust_rcv_timeout(rcd, npkts);
-	qib_write_ureg(rcd->dd, ur_rcvhdrhead, hd, rcd->ctxt);
-	qib_write_ureg(rcd->dd, ur_rcvhdrhead, hd, rcd->ctxt);
 	if (updegr)
 		qib_write_ureg(rcd->dd, ur_rcvegrindexhead, egrhd, rcd->ctxt);
+	mmiowb();
+	qib_write_ureg(rcd->dd, ur_rcvhdrhead, hd, rcd->ctxt);
+	qib_write_ureg(rcd->dd, ur_rcvhdrhead, hd, rcd->ctxt);
+	mmiowb();
 }
 
 static u32 qib_7322_hdrqempty(struct qib_ctxtdata *rcd)