staging/android: sync_debug: unproxify debugfs files' fops

Since commit 49d200d ("debugfs: prevent access to removed files'
private data"), a debugfs file's file_operations methods get proxied
through lifetime aware wrappers.

However, only a certain subset of the file_operations members is supported
by debugfs and ->compat_ioctl isn't among them -- it appears to be NULL
from the VFS layer's perspective.

This behaviour breaks the /sys/kernel/debug/sync/sw_sync file introduced
concurrently with commit a44eb74 ("staging/android: move SW_SYNC_USER
to a debugfs file").

Since that file never gets removed, there is no file removal race and thus,
a lifetime checking proxy isn't needed.

Avoid the proxying for /sys/kernel/debug/sync/sw_sync by creating it via
debugfs_create_file_unsafe() rather than debugfs_create_file().
For consistency, do the same for /sys/kernel/debug/sync/info.

Fixes: 49d200d ("debugfs: prevent access to removed files' private data")
Fixes: a44eb74 ("staging/android: move SW_SYNC_USER to a debugfs file")
Signed-off-by: Nicolai Stange <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/staging/android/sync_debug.c

@@ -189,10 +189,15 @@ static __init int sync_debugfs_init(void)
 {
  dbgfs = debugfs_create_dir("sync", NULL);
 
- debugfs_create_file("info", 0444, dbgfs, NULL, &sync_info_debugfs_fops);
-
- debugfs_create_file("sw_sync", 0644, dbgfs, NULL,
- &sw_sync_debugfs_fops);
+ /*
+ * The debugfs files won't ever get removed and thus, there is
+ * no need to protect it against removal races. The use of
+ * debugfs_create_file_unsafe() is actually safe here.
+ */
+ debugfs_create_file_unsafe("info", 0444, dbgfs, NULL,
+ &sync_info_debugfs_fops);
+ debugfs_create_file_unsafe("sw_sync", 0644, dbgfs, NULL,
+ &sw_sync_debugfs_fops);
 
  return 0;
 }