debugfs: add API to allow debugfs operations cancellation

In some cases there might be longer-running hardware accesses
in debugfs files, or attempts to acquire locks, and we want
to still be able to quickly remove the files.

Introduce a cancellations API to use inside the debugfs handler
functions to be able to cancel such operations on a per-file
basis.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h
index c7d61cfc97d2..0c4c68cf161f 100644
--- a/fs/debugfs/internal.h
+++ b/fs/debugfs/internal.h
@@ -8,6 +8,7 @@
 #ifndef _DEBUGFS_INTERNAL_H_
 #define _DEBUGFS_INTERNAL_H_
 #include <linux/lockdep.h>
+#include <linux/list.h>
 
 struct file_operations;
 
@@ -29,6 +30,10 @@ struct debugfs_fsdata {
 			struct lock_class_key key;
 			char *lock_name;
 #endif
+
+			/* protect cancellations */
+			struct mutex cancellations_mtx;
+			struct list_head cancellations;
 		};
 	};
 };