Messages in this thread Patch in this message | | | From | Nicolai Stange <> | Subject | [PATCH] staging/android: sync_debug: unproxify debugfs files' fops | Date | Fri, 27 May 2016 20:03:54 +0200 |
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Since commit 49d200deaa68 ("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 a44eb74cd413 ("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: 49d200deaa68 ("debugfs: prevent access to removed files' private data") Fixes: a44eb74cd413 ("staging/android: move SW_SYNC_USER to a debugfs file") Signed-off-by: Nicolai Stange <nicstange@gmail.com> --- Applicable to linux-next-20160527. x86_64 allmodconfig build succeeds w/o any new warnings.
Related discussion can be found here: http://lkml.kernel.org/g/878tz22peb.fsf@gmail.com
drivers/staging/android/sync_debug.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/android/sync_debug.c b/drivers/staging/android/sync_debug.c index 5f57499..1197f9e 100644 --- a/drivers/staging/android/sync_debug.c +++ b/drivers/staging/android/sync_debug.c @@ -326,9 +326,15 @@ 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; } -- 2.8.2
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