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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 01/14] uapi: General notification queue definitions [ver #3] From: David Howells To: torvalds@linux-foundation.org Cc: dhowells@redhat.com, Greg Kroah-Hartman , Casey Schaufler , Stephen Smalley , nicolas.dichtel@6wind.com, raven@themaw.net, Christian Brauner , dhowells@redhat.com, keyrings@vger.kernel.org, linux-usb@vger.kernel.org, linux-block@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 15 Jan 2020 13:30:45 +0000 Message-ID: <157909504508.20155.16673561263079184328.stgit@warthog.procyon.org.uk> In-Reply-To: <157909503552.20155.3030058841911628518.stgit@warthog.procyon.org.uk> References: <157909503552.20155.3030058841911628518.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 --- 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 000000000000..5f3d21e8a34b --- /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 + +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 */