IB/qib: Remove s_lock around header validation

Review of qib_ruc_check_hdr() shows that the s_lock is not required in
the normal case.  The r_lock is held in all cases, and protects the qp
fields that are read.

The s_lock will be needed to around the call to qib_migrate_qp() to
insure that the send engine sees a consistent set of fields.
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/qib/qib_driver.c

@@ -310,7 +310,6 @@ static u32 qib_rcv_hdrerr(struct qib_ctxtdata *rcd, struct qib_pportdata *ppd,
 		u32 opcode;
 		u32 psn;
 		int diff;
-		unsigned long flags;
 
 		/* Sanity check packet */
 		if (tlen < 24)
@@ -365,7 +364,6 @@ static u32 qib_rcv_hdrerr(struct qib_ctxtdata *rcd, struct qib_pportdata *ppd,
 
 			switch (qp->ibqp.qp_type) {
 			case IB_QPT_RC:
-				spin_lock_irqsave(&qp->s_lock, flags);
 				ruc_res =
 					qib_ruc_check_hdr(
 						ibp, hdr,
@@ -373,11 +371,8 @@ static u32 qib_rcv_hdrerr(struct qib_ctxtdata *rcd, struct qib_pportdata *ppd,
 						qp,
 						be32_to_cpu(ohdr->bth[0]));
 				if (ruc_res) {
-					spin_unlock_irqrestore(&qp->s_lock,
-							       flags);
 					goto unlock;
 				}
-				spin_unlock_irqrestore(&qp->s_lock, flags);
 
 				/* Only deal with RDMA Writes for now */
 				if (opcode <

drivers/infiniband/hw/qib/qib_rc.c

@@ -1889,10 +1889,8 @@ void qib_rc_rcv(struct qib_ctxtdata *rcd, struct qib_ib_header *hdr,
 	}
 
 	opcode = be32_to_cpu(ohdr->bth[0]);
-	spin_lock_irqsave(&qp->s_lock, flags);
 	if (qib_ruc_check_hdr(ibp, hdr, has_grh, qp, opcode))
-		goto sunlock;
-	spin_unlock_irqrestore(&qp->s_lock, flags);
+		return;
 
 	psn = be32_to_cpu(ohdr->bth[2]);
 	opcode >>= 24;

drivers/infiniband/hw/qib/qib_ruc.c

@@ -260,12 +260,15 @@ static int gid_ok(union ib_gid *gid, __be64 gid_prefix, __be64 id)
 
 /*
  *
- * This should be called with the QP s_lock held.
+ * This should be called with the QP r_lock held.
+ *
+ * The s_lock will be acquired around the qib_migrate_qp() call.
  */
 int qib_ruc_check_hdr(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 		      int has_grh, struct qib_qp *qp, u32 bth0)
 {
 	__be64 guid;
+	unsigned long flags;
 
 	if (qp->s_mig_state == IB_MIG_ARMED && (bth0 & IB_BTH_MIG_REQ)) {
 		if (!has_grh) {
@@ -295,7 +298,9 @@ int qib_ruc_check_hdr(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 		if (be16_to_cpu(hdr->lrh[3]) != qp->alt_ah_attr.dlid ||
 		    ppd_from_ibp(ibp)->port != qp->alt_ah_attr.port_num)
 			goto err;
+		spin_lock_irqsave(&qp->s_lock, flags);
 		qib_migrate_qp(qp);
+		spin_unlock_irqrestore(&qp->s_lock, flags);
 	} else {
 		if (!has_grh) {
 			if (qp->remote_ah_attr.ah_flags & IB_AH_GRH)

drivers/infiniband/hw/qib/qib_uc.c

@@ -243,7 +243,6 @@ void qib_uc_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 		int has_grh, void *data, u32 tlen, struct qib_qp *qp)
 {
 	struct qib_other_headers *ohdr;
-	unsigned long flags;
 	u32 opcode;
 	u32 hdrsize;
 	u32 psn;
@@ -263,10 +262,8 @@ void qib_uc_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 	}
 
 	opcode = be32_to_cpu(ohdr->bth[0]);
-	spin_lock_irqsave(&qp->s_lock, flags);
 	if (qib_ruc_check_hdr(ibp, hdr, has_grh, qp, opcode))
-		goto sunlock;
-	spin_unlock_irqrestore(&qp->s_lock, flags);
+		return;
 
 	psn = be32_to_cpu(ohdr->bth[2]);
 	opcode >>= 24;
@@ -554,6 +551,4 @@ void qib_uc_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 	qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
 	return;
 
-sunlock:
-	spin_unlock_irqrestore(&qp->s_lock, flags);
 }