bnxt_re: Don't issue cmd to delete GID for QP1 GID entry before the QP is destroyed

FW needs the 0th GID Entry in the Table to be preserved before
it's corresponding QP1 is deleted, else it will fail the cmd.
Check for the same and return to prevent error msg being logged for
cmd failure.
Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/bnxt_re/ib_verbs.c

@@ -314,6 +314,7 @@ int bnxt_re_del_gid(struct ib_device *ibdev, u8 port_num,
 	struct bnxt_re_gid_ctx *ctx, **ctx_tbl;
 	struct bnxt_re_dev *rdev = to_bnxt_re_dev(ibdev, ibdev);
 	struct bnxt_qplib_sgid_tbl *sgid_tbl = &rdev->qplib_res.sgid_tbl;
+	struct bnxt_qplib_gid *gid_to_del;
 
 	/* Delete the entry from the hardware */
 	ctx = *context;
@@ -323,11 +324,25 @@ int bnxt_re_del_gid(struct ib_device *ibdev, u8 port_num,
 	if (sgid_tbl && sgid_tbl->active) {
 		if (ctx->idx >= sgid_tbl->max)
 			return -EINVAL;
+		gid_to_del = &sgid_tbl->tbl[ctx->idx];
+		/* DEL_GID is called in WQ context(netdevice_event_work_handler)
+		 * or via the ib_unregister_device path. In the former case QP1
+		 * may not be destroyed yet, in which case just return as FW
+		 * needs that entry to be present and will fail it's deletion.
+		 * We could get invoked again after QP1 is destroyed OR get an
+		 * ADD_GID call with a different GID value for the same index
+		 * where we issue MODIFY_GID cmd to update the GID entry -- TBD
+		 */
+		if (ctx->idx == 0 &&
+		    rdma_link_local_addr((struct in6_addr *)gid_to_del) &&
+		    ctx->refcnt == 1 && rdev->qp1_sqp) {
+			dev_dbg(rdev_to_dev(rdev),
+				"Trying to delete GID0 while QP1 is alive\n");
+			return -EFAULT;
+		}
 		ctx->refcnt--;
 		if (!ctx->refcnt) {
-			rc = bnxt_qplib_del_sgid(sgid_tbl,
-						 &sgid_tbl->tbl[ctx->idx],
-						 true);
+			rc = bnxt_qplib_del_sgid(sgid_tbl, gid_to_del, true);
 			if (rc) {
 				dev_err(rdev_to_dev(rdev),
 					"Failed to remove GID: %#x", rc);
@@ -811,6 +826,8 @@ int bnxt_re_destroy_qp(struct ib_qp *ib_qp)
 
 		kfree(rdev->sqp_ah);
 		kfree(rdev->qp1_sqp);
+		rdev->qp1_sqp = NULL;
+		rdev->sqp_ah = NULL;
 	}
 
 	if (!IS_ERR_OR_NULL(qp->rumem))