From: David Howells dhowells@redhat.com
[ Upstream commit 0858caa419e6cf9d31e734d09d70b34f64443ef6 ]
Add UAPI definitions for the general notification queue, including the following pieces:
(*) struct watch_notification.
This is the metadata header for notification messages. It includes a type and subtype that indicate the source of the message (eg. WATCH_TYPE_MOUNT_NOTIFY) and the kind of the message (eg. NOTIFY_MOUNT_NEW_MOUNT).
The header also contains an information field that conveys the following information:
- WATCH_INFO_LENGTH. The size of the entry (entries are variable length).
- WATCH_INFO_ID. The watch ID specified when the watchpoint was set.
- WATCH_INFO_TYPE_INFO. (Sub)type-specific information.
- WATCH_INFO_FLAG_*. Flag bits overlain on the type-specific information. For use by the type.
All the information in the header can be used in filtering messages at the point of writing into the buffer.
(*) struct watch_notification_removal
This is an extended watch-removal notification record that includes an 'id' field that can indicate the identifier of the object being removed if available (for instance, a keyring serial number).
Signed-off-by: David Howells dhowells@redhat.com Stable-dep-of: d55901522f96 ("keys: Fix linking a duplicate key to a keyring's assoc_array") Signed-off-by: Sasha Levin sashal@kernel.org --- include/uapi/linux/watch_queue.h | 55 ++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 include/uapi/linux/watch_queue.h
diff --git a/include/uapi/linux/watch_queue.h b/include/uapi/linux/watch_queue.h new file mode 100644 index 0000000000000..5f3d21e8a34b0 --- /dev/null +++ b/include/uapi/linux/watch_queue.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI_LINUX_WATCH_QUEUE_H +#define _UAPI_LINUX_WATCH_QUEUE_H + +#include <linux/types.h> + +enum watch_notification_type { + WATCH_TYPE_META = 0, /* Special record */ + WATCH_TYPE__NR = 1 +}; + +enum watch_meta_notification_subtype { + WATCH_META_REMOVAL_NOTIFICATION = 0, /* Watched object was removed */ + WATCH_META_LOSS_NOTIFICATION = 1, /* Data loss occurred */ +}; + +/* + * Notification record header. This is aligned to 64-bits so that subclasses + * can contain __u64 fields. + */ +struct watch_notification { + __u32 type:24; /* enum watch_notification_type */ + __u32 subtype:8; /* Type-specific subtype (filterable) */ + __u32 info; +#define WATCH_INFO_LENGTH 0x0000007f /* Length of record */ +#define WATCH_INFO_LENGTH__SHIFT 0 +#define WATCH_INFO_ID 0x0000ff00 /* ID of watchpoint */ +#define WATCH_INFO_ID__SHIFT 8 +#define WATCH_INFO_TYPE_INFO 0xffff0000 /* Type-specific info */ +#define WATCH_INFO_TYPE_INFO__SHIFT 16 +#define WATCH_INFO_FLAG_0 0x00010000 /* Type-specific info, flag bit 0 */ +#define WATCH_INFO_FLAG_1 0x00020000 /* ... */ +#define WATCH_INFO_FLAG_2 0x00040000 +#define WATCH_INFO_FLAG_3 0x00080000 +#define WATCH_INFO_FLAG_4 0x00100000 +#define WATCH_INFO_FLAG_5 0x00200000 +#define WATCH_INFO_FLAG_6 0x00400000 +#define WATCH_INFO_FLAG_7 0x00800000 +}; + + +/* + * Extended watch removal notification. This is used optionally if the type + * wants to indicate an identifier for the object being watched, if there is + * such. This can be distinguished by the length. + * + * type -> WATCH_TYPE_META + * subtype -> WATCH_META_REMOVAL_NOTIFICATION + */ +struct watch_notification_removal { + struct watch_notification watch; + __u64 id; /* Type-dependent identifier */ +}; + +#endif /* _UAPI_LINUX_WATCH_QUEUE_H */