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1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _UAPI_LINUX_WATCH_QUEUE_H
3 #define _UAPI_LINUX_WATCH_QUEUE_H
4 
5 #include <linux/types.h>
6 
7 enum watch_notification_type {
8 	WATCH_TYPE_META		= 0,	/* Special record */
9 	WATCH_TYPE__NR		= 1
10 };
11 
12 enum watch_meta_notification_subtype {
13 	WATCH_META_REMOVAL_NOTIFICATION	= 0,	/* Watched object was removed */
14 	WATCH_META_LOSS_NOTIFICATION	= 1,	/* Data loss occurred */
15 };
16 
17 /*
18  * Notification record header.  This is aligned to 64-bits so that subclasses
19  * can contain __u64 fields.
20  */
21 struct watch_notification {
22 	__u32			type:24;	/* enum watch_notification_type */
23 	__u32			subtype:8;	/* Type-specific subtype (filterable) */
24 	__u32			info;
25 #define WATCH_INFO_LENGTH	0x0000007f	/* Length of record */
26 #define WATCH_INFO_LENGTH__SHIFT 0
27 #define WATCH_INFO_ID		0x0000ff00	/* ID of watchpoint */
28 #define WATCH_INFO_ID__SHIFT	8
29 #define WATCH_INFO_TYPE_INFO	0xffff0000	/* Type-specific info */
30 #define WATCH_INFO_TYPE_INFO__SHIFT 16
31 #define WATCH_INFO_FLAG_0	0x00010000	/* Type-specific info, flag bit 0 */
32 #define WATCH_INFO_FLAG_1	0x00020000	/* ... */
33 #define WATCH_INFO_FLAG_2	0x00040000
34 #define WATCH_INFO_FLAG_3	0x00080000
35 #define WATCH_INFO_FLAG_4	0x00100000
36 #define WATCH_INFO_FLAG_5	0x00200000
37 #define WATCH_INFO_FLAG_6	0x00400000
38 #define WATCH_INFO_FLAG_7	0x00800000
39 };
40 
41 
42 /*
43  * Extended watch removal notification.  This is used optionally if the type
44  * wants to indicate an identifier for the object being watched, if there is
45  * such.  This can be distinguished by the length.
46  *
47  * type -> WATCH_TYPE_META
48  * subtype -> WATCH_META_REMOVAL_NOTIFICATION
49  */
50 struct watch_notification_removal {
51 	struct watch_notification watch;
52 	__u64	id;		/* Type-dependent identifier */
53 };
54 
55 #endif /* _UAPI_LINUX_WATCH_QUEUE_H */
56