IB/core: Change completion channel to use the reworked objects schema

This patch adds the standard fd based type - completion_channel.
The completion_channel is now prefixed with ib_uobject, similarly
to the rest of the uobjects.
This requires a few changes:
(1) We define a new completion channel fd based object type.
(2) completion_event and async_event are now two different types.
    This means they use different fops.
(3) We release the completion_channel exactly as we release other
    idr based objects.
(4) Since ib_uobjects are already kref-ed, we only add the kref to the
    async event.

A fd object requires filling out several parameters. Its op pointer
should point to uverbs_fd_ops and its size should be at least the
size if ib_uobject. We use a macro to make the type declaration
easier.

Signed-off-by: Matan Barak <matanb@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/uverbs.h

@@ -102,25 +102,33 @@ struct ib_uverbs_device {
 };
 
 struct ib_uverbs_event_file {
-	struct kref				ref;
-	int					is_async;
-	struct ib_uverbs_file		       *uverbs_file;
 	spinlock_t				lock;
 	int					is_closed;
 	wait_queue_head_t			poll_wait;
 	struct fasync_struct		       *async_queue;
 	struct list_head			event_list;
+};
+
+struct ib_uverbs_async_event_file {
+	struct ib_uverbs_event_file		ev_file;
+	struct ib_uverbs_file		       *uverbs_file;
+	struct kref				ref;
 	struct list_head			list;
 };
 
+struct ib_uverbs_completion_event_file {
+	struct ib_uobject_file			uobj_file;
+	struct ib_uverbs_event_file		ev_file;
+};
+
 struct ib_uverbs_file {
 	struct kref				ref;
 	struct mutex				mutex;
 	struct mutex                            cleanup_mutex; /* protect cleanup */
 	struct ib_uverbs_device		       *device;
 	struct ib_ucontext		       *ucontext;
 	struct ib_event_handler			event_handler;
-	struct ib_uverbs_event_file	       *async_file;
+	struct ib_uverbs_async_event_file       *async_file;
 	struct list_head			list;
 	int					is_closed;
 
@@ -182,14 +190,14 @@ struct ib_ucq_object {
 	u32			async_events_reported;
 };
 
-struct file *ib_uverbs_alloc_event_file(struct ib_uverbs_file *uverbs_file,
-					struct ib_device *ib_dev,
-					int is_async);
+extern const struct file_operations uverbs_event_fops;
+void ib_uverbs_init_event_file(struct ib_uverbs_event_file *ev_file);
+struct file *ib_uverbs_alloc_async_event_file(struct ib_uverbs_file *uverbs_file,
+					      struct ib_device *ib_dev);
 void ib_uverbs_free_async_event_file(struct ib_uverbs_file *uverbs_file);
-struct ib_uverbs_event_file *ib_uverbs_lookup_comp_file(int fd);
 
 void ib_uverbs_release_ucq(struct ib_uverbs_file *file,
-			   struct ib_uverbs_event_file *ev_file,
+			   struct ib_uverbs_completion_event_file *ev_file,
 			   struct ib_ucq_object *uobj);
 void ib_uverbs_release_uevent(struct ib_uverbs_file *file,
 			      struct ib_uevent_object *uobj);

drivers/infiniband/core/uverbs_cmd.c

@@ -47,6 +47,24 @@
 #include "uverbs.h"
 #include "core_priv.h"
 
+static struct ib_uverbs_completion_event_file *
+ib_uverbs_lookup_comp_file(int fd, struct ib_ucontext *context)
+{
+	struct ib_uobject *uobj = uobj_get_read(uobj_get_type(comp_channel),
+						fd, context);
+	struct ib_uobject_file *uobj_file;
+
+	if (IS_ERR(uobj))
+		return (void *)uobj;
+
+	uverbs_uobject_get(uobj);
+	uobj_put_read(uobj);
+
+	uobj_file = container_of(uobj, struct ib_uobject_file, uobj);
+	return container_of(uobj_file, struct ib_uverbs_completion_event_file,
+			    uobj_file);
+}
+
 ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
 			      struct ib_device *ib_dev,
 			      const char __user *buf,
@@ -116,7 +134,7 @@ ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
 		goto err_free;
 	resp.async_fd = ret;
 
-	filp = ib_uverbs_alloc_event_file(file, ib_dev, 1);
+	filp = ib_uverbs_alloc_async_event_file(file, ib_dev);
 	if (IS_ERR(filp)) {
 		ret = PTR_ERR(filp);
 		goto err_fd;
@@ -908,34 +926,32 @@ ssize_t ib_uverbs_create_comp_channel(struct ib_uverbs_file *file,
 {
 	struct ib_uverbs_create_comp_channel	   cmd;
 	struct ib_uverbs_create_comp_channel_resp  resp;
-	struct file				  *filp;
-	int ret;
+	struct ib_uobject			  *uobj;
+	struct ib_uverbs_completion_event_file	  *ev_file;
 
 	if (out_len < sizeof resp)
 		return -ENOSPC;
 
 	if (copy_from_user(&cmd, buf, sizeof cmd))
 		return -EFAULT;
 
-	ret = get_unused_fd_flags(O_CLOEXEC);
-	if (ret < 0)
-		return ret;
-	resp.fd = ret;
+	uobj = uobj_alloc(uobj_get_type(comp_channel), file->ucontext);
+	if (IS_ERR(uobj))
+		return PTR_ERR(uobj);
 
-	filp = ib_uverbs_alloc_event_file(file, ib_dev, 0);
-	if (IS_ERR(filp)) {
-		put_unused_fd(resp.fd);
-		return PTR_ERR(filp);
-	}
+	resp.fd = uobj->id;
+
+	ev_file = container_of(uobj, struct ib_uverbs_completion_event_file,
+			       uobj_file.uobj);
+	ib_uverbs_init_event_file(&ev_file->ev_file);
 
 	if (copy_to_user((void __user *) (unsigned long) cmd.response,
 			 &resp, sizeof resp)) {
-		put_unused_fd(resp.fd);
-		fput(filp);
+		uobj_alloc_abort(uobj);
 		return -EFAULT;
 	}
 
-	fd_install(resp.fd, filp);
+	uobj_alloc_commit(uobj);
 	return in_len;
 }
 
@@ -953,7 +969,7 @@ static struct ib_ucq_object *create_cq(struct ib_uverbs_file *file,
 				       void *context)
 {
 	struct ib_ucq_object           *obj;
-	struct ib_uverbs_event_file    *ev_file = NULL;
+	struct ib_uverbs_completion_event_file    *ev_file = NULL;
 	struct ib_cq                   *cq;
 	int                             ret;
 	struct ib_uverbs_ex_create_cq_resp resp;
@@ -968,9 +984,10 @@ static struct ib_ucq_object *create_cq(struct ib_uverbs_file *file,
 		return obj;
 
 	if (cmd->comp_channel >= 0) {
-		ev_file = ib_uverbs_lookup_comp_file(cmd->comp_channel);
-		if (!ev_file) {
-			ret = -EINVAL;
+		ev_file = ib_uverbs_lookup_comp_file(cmd->comp_channel,
+						     file->ucontext);
+		if (IS_ERR(ev_file)) {
+			ret = PTR_ERR(ev_file);
 			goto err;
 		}
 	}
@@ -998,7 +1015,7 @@ static struct ib_ucq_object *create_cq(struct ib_uverbs_file *file,
 	cq->uobject       = &obj->uobject;
 	cq->comp_handler  = ib_uverbs_comp_handler;
 	cq->event_handler = ib_uverbs_cq_event_handler;
-	cq->cq_context    = ev_file;
+	cq->cq_context    = &ev_file->ev_file;
 	atomic_set(&cq->usecnt, 0);
 
 	obj->uobject.object = cq;