Fix create/destroy flow API

When adding this API, there had been consensus that having separate
lib_* and drv_* function pointers in the extended context struct
was not needed and should not be done.  However, that snuck in anyway.
This backs that out and takes us back to a single pointer for each
function, but does so in a way as to preserve both back and forward
compatibility.

Fixes: 389de6a6ef4e (Add receive flow steering support)
Signed-off-by: Doug Ledford <dledford@redhat.com>

2 files changed, 24 insertions, 23 deletions

diff --git a/include/infiniband/verbs.h b/include/infiniband/verbs.h
index 28e1586..6100f52 100644
--- a/include/infiniband/verbs.h
+++ b/include/infiniband/verbs.h
@@ -977,14 +977,11 @@ enum verbs_context_mask {
 
 struct verbs_context {
 	/*  "grows up" - new fields go here */
-	int (*drv_ibv_destroy_flow) (struct ibv_flow *flow);
-	int (*lib_ibv_destroy_flow) (struct ibv_flow *flow);
-	struct ibv_flow * (*drv_ibv_create_flow) (struct ibv_qp *qp,
-						  struct ibv_flow_attr
-						  *flow_attr);
-	struct ibv_flow * (*lib_ibv_create_flow) (struct ibv_qp *qp,
-						  struct ibv_flow_attr
-						  *flow_attr);
+	int (*ibv_destroy_flow) (struct ibv_flow *flow);
+	void (*ABI_placeholder2) (void); /* DO NOT COPY THIS GARBAGE */
+	struct ibv_flow * (*ibv_create_flow) (struct ibv_qp *qp,
+					      struct ibv_flow_attr *flow_attr);
+	void (*ABI_placeholder1) (void); /* DO NOT COPY THIS GARBAGE */
 	struct ibv_qp *(*open_qp)(struct ibv_context *context,
 			struct ibv_qp_open_attr *attr);
 	struct ibv_qp *(*create_qp_ex)(struct ibv_context *context,
@@ -1137,20 +1134,20 @@ static inline struct ibv_flow *ibv_create_flow(struct ibv_qp *qp,
 					       struct ibv_flow_attr *flow)
 {
 	struct verbs_context *vctx = verbs_get_ctx_op(qp->context,
-						      lib_ibv_create_flow);
-	if (!vctx || !vctx->lib_ibv_create_flow)
+						      ibv_create_flow);
+	if (!vctx || !vctx->ibv_create_flow)
 		return NULL;
 
-	return vctx->lib_ibv_create_flow(qp, flow);
+	return vctx->ibv_create_flow(qp, flow);
 }
 
 static inline int ibv_destroy_flow(struct ibv_flow *flow_id)
 {
 	struct verbs_context *vctx = verbs_get_ctx_op(flow_id->context,
-						      lib_ibv_destroy_flow);
-	if (!vctx || !vctx->lib_ibv_destroy_flow)
+						      ibv_destroy_flow);
+	if (!vctx || !vctx->ibv_destroy_flow)
 		return -ENOSYS;
-	return vctx->lib_ibv_destroy_flow(flow_id);
+	return vctx->ibv_destroy_flow(flow_id);
 }
 
 /**
diff --git a/src/device.c b/src/device.c
index 9642ead..f2b889c 100644
--- a/src/device.c
+++ b/src/device.c
@@ -163,16 +163,20 @@ struct ibv_context *__ibv_open_device(struct ibv_device *device)
 		ret = verbs_device->init_context(verbs_device, context, cmd_fd);
 		if (ret)
 			goto verbs_err;
-
-		/* initialize *all* library ops to either lib calls or
-		 * directly to provider calls.
-		 * context_ex->lib_new_func1 = __verbs_new_func1;
-		 * context_ex->lib_new_func2 = __verbs_new_func2;
+		/*
+		 * In order to maintain backward/forward binary compatibility
+		 * with apps compiled against libibverbs-1.1.8 that use the
+		 * flow steering addition, we need to set the two
+		 * ABI_placeholder entries to match the driver set flow
+		 * entries.  This is because apps compiled against
+		 * libibverbs-1.1.8 use an inline ibv_create_flow and
+		 * ibv_destroy_flow function that looks in the placeholder
+		 * spots for the proper entry points.  For apps compiled
+		 * against libibverbs-1.1.9 and later, the inline functions
+		 * will be looking in the right place.
 		 */
-		 context_ex->lib_ibv_create_flow =
-			 context_ex->drv_ibv_create_flow;
-		 context_ex->lib_ibv_destroy_flow =
-			 context_ex->drv_ibv_destroy_flow;
+		context_ex->ABI_placeholder1 = (void (*)(void)) context_ex->ibv_create_flow;
+		context_ex->ABI_placeholder2 = (void (*)(void)) context_ex->ibv_destroy_flow;
 	}
 
 	context->device = device;