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Subject[PATCH 4.14 086/101] drm/syncobj: Stop reusing the same struct file for all syncobj -> fd
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Wilson <chris@chris-wilson.co.uk>

commit e7cdf5c82f1773c3386b93bbcf13b9bfff29fa31 upstream.

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]
v2.2: [jekstrand: back-port to 4.14]

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>
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Tested-by: Clayton Craft <clayton.a.craft@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/drm_syncobj.c | 81 +++++++++++++++---------------------------
include/drm/drm_syncobj.h | 5 --
2 files changed, 30 insertions(+), 56 deletions(-)

--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -328,28 +328,11 @@ static const struct file_operations drm_
.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;
-}
-
static int drm_syncobj_handle_to_fd(struct drm_file *file_private,
u32 handle, int *p_fd)
{
struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
- int ret;
+ struct file *file;
int fd;

if (!syncobj)
@@ -361,46 +344,40 @@ static int drm_syncobj_handle_to_fd(stru
return fd;
}

- if (!syncobj->file) {
- ret = drm_syncobj_alloc_file(syncobj);
- if (ret)
- goto out_put_fd;
+ file = anon_inode_getfile("syncobj_file",
+ &drm_syncobj_file_fops,
+ syncobj, 0);
+ if (IS_ERR(file)) {
+ put_unused_fd(fd);
+ drm_syncobj_put(syncobj);
+ return PTR_ERR(file);
}
- fd_install(fd, syncobj->file);
- drm_syncobj_put(syncobj);
+
+ drm_syncobj_get(syncobj);
+ fd_install(fd, file);
+
*p_fd = fd;
return 0;
-out_put_fd:
- put_unused_fd(fd);
- drm_syncobj_put(syncobj);
- 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);
@@ -409,12 +386,14 @@ static int drm_syncobj_fd_to_handle(stru
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;
}

int drm_syncobj_import_sync_file_fence(struct drm_file *file_private,
--- a/include/drm/drm_syncobj.h
+++ b/include/drm/drm_syncobj.h
@@ -60,11 +60,6 @@ struct drm_syncobj {
* locks cb_list and write-locks fence.
*/
spinlock_t lock;
- /**
- * @file:
- * a file backing for this syncobj.
- */
- struct file *file;
};

typedef void (*drm_syncobj_func_t)(struct drm_syncobj *syncobj,

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