IB/uverbs: Make the write path destroy methods use the same flow as ioctl

The ridiculous dance with uobj_remove_commit() is not needed, the write
path can follow the same flow as ioctl - lock and destroy the HW object
then use the data left over in the uobject to form the response to
userspace.

Two helpers are introduced to make this flow straightforward for the
caller.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/rdma_core.c

@@ -130,24 +130,44 @@ static int uverbs_try_lock_object(struct ib_uobject *uobj, bool exclusive)
 }
 
 /*
- * Does both rdma_lookup_get_uobject() and rdma_remove_commit_uobject(), then
- * returns success_res on success (negative errno on failure). For use by
- * callers that do not need the uobj.
+ * uobj_get_destroy destroys the HW object and returns a handle to the uobj
+ * with a NULL object pointer. The caller must pair this with
+ * uverbs_put_destroy.
  */
-int __uobj_perform_destroy(const struct uverbs_obj_type *type, u32 id,
-			   struct ib_uverbs_file *ufile, int success_res)
+struct ib_uobject *__uobj_get_destroy(const struct uverbs_obj_type *type,
+				      u32 id, struct ib_uverbs_file *ufile)
 {
 	struct ib_uobject *uobj;
 	int ret;
 
 	uobj = rdma_lookup_get_uobject(type, ufile, id, true);
 	if (IS_ERR(uobj))
-		return PTR_ERR(uobj);
+		return uobj;
 
-	ret = rdma_remove_commit_uobject(uobj);
-	if (ret)
-		return ret;
+	ret = rdma_explicit_destroy(uobj);
+	if (ret) {
+		rdma_lookup_put_uobject(uobj, true);
+		return ERR_PTR(ret);
+	}
+
+	return uobj;
+}
 
+/*
+ * Does both uobj_get_destroy() and uobj_put_destroy().  Returns success_res
+ * on success (negative errno on failure). For use by callers that do not need
+ * the uobj.
+ */
+int __uobj_perform_destroy(const struct uverbs_obj_type *type, u32 id,
+			   struct ib_uverbs_file *ufile, int success_res)
+{
+	struct ib_uobject *uobj;
+
+	uobj = __uobj_get_destroy(type, id, ufile);
+	if (IS_ERR(uobj))
+		return PTR_ERR(uobj);
+
+	rdma_lookup_put_uobject(uobj, true);
 	return success_res;
 }
 
@@ -449,21 +469,6 @@ static int __must_check _rdma_remove_commit_uobject(struct ib_uobject *uobj,
 	return ret;
 }
 
-/* This is called only for user requested DESTROY reasons
- * rdma_lookup_get_uobject(exclusive=true) must have been called to get uobj,
- * and after this returns the corresponding put has been done, and the kref
- * for uobj has been consumed.
- */
-int __must_check rdma_remove_commit_uobject(struct ib_uobject *uobj)
-{
-	int ret;
-
-	ret = rdma_explicit_destroy(uobj);
-	/* Pairs with the lookup_get done by the caller */
-	rdma_lookup_put_uobject(uobj, true);
-	return ret;
-}
-
 int rdma_explicit_destroy(struct ib_uobject *uobject)
 {
 	int ret;

drivers/infiniband/core/uverbs_cmd.c

@@ -1304,37 +1304,22 @@ ssize_t ib_uverbs_destroy_cq(struct ib_uverbs_file *file,
 	struct ib_uverbs_destroy_cq      cmd;
 	struct ib_uverbs_destroy_cq_resp resp;
 	struct ib_uobject		*uobj;
-	struct ib_cq               	*cq;
 	struct ib_ucq_object        	*obj;
-	int                        	 ret = -EINVAL;
 
 	if (copy_from_user(&cmd, buf, sizeof cmd))
 		return -EFAULT;
 
-	uobj = uobj_get_write(UVERBS_OBJECT_CQ, cmd.cq_handle, file);
+	uobj = uobj_get_destroy(UVERBS_OBJECT_CQ, cmd.cq_handle, file);
 	if (IS_ERR(uobj))
 		return PTR_ERR(uobj);
 
-	/*
-	 * Make sure we don't free the memory in remove_commit as we still
-	 * needs the uobject memory to create the response.
-	 */
-	uverbs_uobject_get(uobj);
-	cq      = uobj->object;
-	obj     = container_of(cq->uobject, struct ib_ucq_object, uobject);
-
+	obj = container_of(uobj, struct ib_ucq_object, uobject);
 	memset(&resp, 0, sizeof(resp));
-
-	ret = uobj_remove_commit(uobj);
-	if (ret) {
-		uverbs_uobject_put(uobj);
-		return ret;
-	}
-
 	resp.comp_events_reported  = obj->comp_events_reported;
 	resp.async_events_reported = obj->async_events_reported;
 
-	uverbs_uobject_put(uobj);
+	uobj_put_destroy(uobj);
+
 	if (copy_to_user(u64_to_user_ptr(cmd.response), &resp, sizeof resp))
 		return -EFAULT;
 
@@ -2104,32 +2089,19 @@ ssize_t ib_uverbs_destroy_qp(struct ib_uverbs_file *file,
 	struct ib_uverbs_destroy_qp_resp resp;
 	struct ib_uobject		*uobj;
 	struct ib_uqp_object        	*obj;
-	int                        	 ret = -EINVAL;
 
 	if (copy_from_user(&cmd, buf, sizeof cmd))
 		return -EFAULT;
 
-	memset(&resp, 0, sizeof resp);
-
-	uobj = uobj_get_write(UVERBS_OBJECT_QP, cmd.qp_handle, file);
+	uobj = uobj_get_destroy(UVERBS_OBJECT_QP, cmd.qp_handle, file);
 	if (IS_ERR(uobj))
 		return PTR_ERR(uobj);
 
 	obj = container_of(uobj, struct ib_uqp_object, uevent.uobject);
-	/*
-	 * Make sure we don't free the memory in remove_commit as we still
-	 * needs the uobject memory to create the response.
-	 */
-	uverbs_uobject_get(uobj);
-
-	ret = uobj_remove_commit(uobj);
-	if (ret) {
-		uverbs_uobject_put(uobj);
-		return ret;
-	}
-
+	memset(&resp, 0, sizeof(resp));
 	resp.events_reported = obj->uevent.events_reported;
-	uverbs_uobject_put(uobj);
+
+	uobj_put_destroy(uobj);
 
 	if (copy_to_user(u64_to_user_ptr(cmd.response), &resp, sizeof resp))
 		return -EFAULT;
@@ -3198,22 +3170,14 @@ int ib_uverbs_ex_destroy_wq(struct ib_uverbs_file *file,
 		return -EOPNOTSUPP;
 
 	resp.response_length = required_resp_len;
-	uobj = uobj_get_write(UVERBS_OBJECT_WQ, cmd.wq_handle, file);
+	uobj = uobj_get_destroy(UVERBS_OBJECT_WQ, cmd.wq_handle, file);
 	if (IS_ERR(uobj))
 		return PTR_ERR(uobj);
 
 	obj = container_of(uobj, struct ib_uwq_object, uevent.uobject);
-	/*
-	 * Make sure we don't free the memory in remove_commit as we still
-	 * needs the uobject memory to create the response.
-	 */
-	uverbs_uobject_get(uobj);
-
-	ret = uobj_remove_commit(uobj);
 	resp.events_reported = obj->uevent.events_reported;
-	uverbs_uobject_put(uobj);
-	if (ret)
-		return ret;
+
+	uobj_put_destroy(uobj);
 
 	return ib_copy_to_udata(ucore, &resp, resp.response_length);
 }
@@ -3920,31 +3884,20 @@ ssize_t ib_uverbs_destroy_srq(struct ib_uverbs_file *file,
 	struct ib_uverbs_destroy_srq_resp resp;
 	struct ib_uobject		 *uobj;
 	struct ib_uevent_object        	 *obj;
-	int                         	  ret = -EINVAL;
 
 	if (copy_from_user(&cmd, buf, sizeof cmd))
 		return -EFAULT;
 
-	uobj = uobj_get_write(UVERBS_OBJECT_SRQ, cmd.srq_handle, file);
+	uobj = uobj_get_destroy(UVERBS_OBJECT_SRQ, cmd.srq_handle, file);
 	if (IS_ERR(uobj))
 		return PTR_ERR(uobj);
 
 	obj = container_of(uobj, struct ib_uevent_object, uobject);
-	/*
-	 * Make sure we don't free the memory in remove_commit as we still
-	 * needs the uobject memory to create the response.
-	 */
-	uverbs_uobject_get(uobj);
-
 	memset(&resp, 0, sizeof(resp));
-
-	ret = uobj_remove_commit(uobj);
-	if (ret) {
-		uverbs_uobject_put(uobj);
-		return ret;
-	}
 	resp.events_reported = obj->events_reported;
-	uverbs_uobject_put(uobj);
+
+	uobj_put_destroy(uobj);
+
 	if (copy_to_user(u64_to_user_ptr(cmd.response), &resp, sizeof(resp)))
 		return -EFAULT;
 

include/rdma/uverbs_std_types.h

@@ -84,6 +84,17 @@ int __uobj_perform_destroy(const struct uverbs_obj_type *type, u32 id,
 	__uobj_perform_destroy(uobj_get_type(_type), _uobj_check_id(_id),      \
 			       _ufile, _success_res)
 
+struct ib_uobject *__uobj_get_destroy(const struct uverbs_obj_type *type,
+				      u32 id, struct ib_uverbs_file *ufile);
+
+#define uobj_get_destroy(_type, _id, _ufile)                                   \
+	__uobj_get_destroy(uobj_get_type(_type), _uobj_check_id(_id), _ufile)
+
+static inline void uobj_put_destroy(struct ib_uobject *uobj)
+{
+	rdma_lookup_put_uobject(uobj, true);
+}
+
 static inline void uobj_put_read(struct ib_uobject *uobj)
 {
 	rdma_lookup_put_uobject(uobj, false);
@@ -97,11 +108,6 @@ static inline void uobj_put_write(struct ib_uobject *uobj)
 	rdma_lookup_put_uobject(uobj, true);
 }
 
-static inline int __must_check uobj_remove_commit(struct ib_uobject *uobj)
-{
-	return rdma_remove_commit_uobject(uobj);
-}
-
 static inline int __must_check uobj_alloc_commit(struct ib_uobject *uobj,
 						 int success_res)
 {

include/rdma/uverbs_types.h

@@ -126,7 +126,6 @@ void rdma_lookup_put_uobject(struct ib_uobject *uobj, bool exclusive);
 struct ib_uobject *rdma_alloc_begin_uobject(const struct uverbs_obj_type *type,
 					    struct ib_uverbs_file *ufile);
 void rdma_alloc_abort_uobject(struct ib_uobject *uobj);
-int __must_check rdma_remove_commit_uobject(struct ib_uobject *uobj);
 int __must_check rdma_alloc_commit_uobject(struct ib_uobject *uobj);
 int rdma_explicit_destroy(struct ib_uobject *uobject);