drm/syncobj: Stop reusing the same struct file for all syncobj -> fd

The vk cts test:
dEQP-VK.api.external.semaphore.opaque_fd.export_multiple_times_temporary

triggers a lot of
VFS: Close: file count is 0

Dave pointed out that clearing the syncobj->file from
drm_syncobj_file_release() was sufficient to silence the test, but that
opens a can of worm since we assumed that the syncobj->file was never
unset. Stop trying to reuse the same struct file for every fd pointing
to the drm_syncobj, and allocate one file for each fd instead.

v2: Fixup return handling of drm_syncobj_fd_to_handle
v2.1: [airlied: fix possible syncobj ref race]

Reported-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index f776fc1..cb4d09c 100644 (file)
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -369,40 +369,26 @@ static const struct file_operations drm_syncobj_file_fops = {
        .release = drm_syncobj_file_release,
 };
 
-static int drm_syncobj_alloc_file(struct drm_syncobj *syncobj)
-{
-       struct file *file = anon_inode_getfile("syncobj_file",
-                                              &drm_syncobj_file_fops,
-                                              syncobj, 0);
-       if (IS_ERR(file))
-               return PTR_ERR(file);
-
-       drm_syncobj_get(syncobj);
-       if (cmpxchg(&syncobj->file, NULL, file)) {
-               /* lost the race */
-               fput(file);
-       }
-
-       return 0;
-}
-
 int drm_syncobj_get_fd(struct drm_syncobj *syncobj, int *p_fd)
 {
-       int ret;
+       struct file *file;
        int fd;
 
        fd = get_unused_fd_flags(O_CLOEXEC);
        if (fd < 0)
                return fd;
 
-       if (!syncobj->file) {
-               ret = drm_syncobj_alloc_file(syncobj);
-               if (ret) {
-                       put_unused_fd(fd);
-                       return ret;
-               }
+       file = anon_inode_getfile("syncobj_file",
+                                 &drm_syncobj_file_fops,
+                                 syncobj, 0);
+       if (IS_ERR(file)) {
+               put_unused_fd(fd);
+               return PTR_ERR(file);
        }
-       fd_install(fd, syncobj->file);
+
+       drm_syncobj_get(syncobj);
+       fd_install(fd, file);
+
        *p_fd = fd;
        return 0;
 }
@@ -422,31 +408,24 @@ static int drm_syncobj_handle_to_fd(struct drm_file *file_private,
        return ret;
 }
 
-static struct drm_syncobj *drm_syncobj_fdget(int fd)
-{
-       struct file *file = fget(fd);
-
-       if (!file)
-               return NULL;
-       if (file->f_op != &drm_syncobj_file_fops)
-               goto err;
-
-       return file->private_data;
-err:
-       fput(file);
-       return NULL;
-};
-
 static int drm_syncobj_fd_to_handle(struct drm_file *file_private,
                                    int fd, u32 *handle)
 {
-       struct drm_syncobj *syncobj = drm_syncobj_fdget(fd);
+       struct drm_syncobj *syncobj;
+       struct file *file;
        int ret;
 
-       if (!syncobj)
+       file = fget(fd);
+       if (!file)
                return -EINVAL;
 
+       if (file->f_op != &drm_syncobj_file_fops) {
+               fput(file);
+               return -EINVAL;
+       }
+
        /* take a reference to put in the idr */
+       syncobj = file->private_data;
        drm_syncobj_get(syncobj);
 
        idr_preload(GFP_KERNEL);
@@ -455,12 +434,14 @@ static int drm_syncobj_fd_to_handle(struct drm_file *file_private,
        spin_unlock(&file_private->syncobj_table_lock);
        idr_preload_end();
 
-       if (ret < 0) {
-               fput(syncobj->file);
-               return ret;
-       }
-       *handle = ret;
-       return 0;
+       if (ret > 0) {
+               *handle = ret;
+               ret = 0;
+       } else
+               drm_syncobj_put(syncobj);
+
+       fput(file);
+       return ret;
 }
 
 static int drm_syncobj_import_sync_file_fence(struct drm_file *file_private,