linux_dsm_epyc7002/include/uapi/linux/dlm_device.h
Gustavo A. R. Silva d6cdad8703 uapi: linux: dlm_device.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00

110 lines
2.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/******************************************************************************
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
** Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
** of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/
#ifndef _LINUX_DLM_DEVICE_H
#define _LINUX_DLM_DEVICE_H
/* This is the device interface for dlm, most users will use a library
* interface.
*/
#include <linux/dlm.h>
#include <linux/types.h>
#define DLM_USER_LVB_LEN 32
/* Version of the device interface */
#define DLM_DEVICE_VERSION_MAJOR 6
#define DLM_DEVICE_VERSION_MINOR 0
#define DLM_DEVICE_VERSION_PATCH 2
/* struct passed to the lock write */
struct dlm_lock_params {
__u8 mode;
__u8 namelen;
__u16 unused;
__u32 flags;
__u32 lkid;
__u32 parent;
__u64 xid;
__u64 timeout;
void __user *castparam;
void __user *castaddr;
void __user *bastparam;
void __user *bastaddr;
struct dlm_lksb __user *lksb;
char lvb[DLM_USER_LVB_LEN];
char name[];
};
struct dlm_lspace_params {
__u32 flags;
__u32 minor;
char name[];
};
struct dlm_purge_params {
__u32 nodeid;
__u32 pid;
};
struct dlm_write_request {
__u32 version[3];
__u8 cmd;
__u8 is64bit;
__u8 unused[2];
union {
struct dlm_lock_params lock;
struct dlm_lspace_params lspace;
struct dlm_purge_params purge;
} i;
};
struct dlm_device_version {
__u32 version[3];
};
/* struct read from the "device" fd,
consists mainly of userspace pointers for the library to use */
struct dlm_lock_result {
__u32 version[3];
__u32 length;
void __user * user_astaddr;
void __user * user_astparam;
struct dlm_lksb __user * user_lksb;
struct dlm_lksb lksb;
__u8 bast_mode;
__u8 unused[3];
/* Offsets may be zero if no data is present */
__u32 lvb_offset;
};
/* Commands passed to the device */
#define DLM_USER_LOCK 1
#define DLM_USER_UNLOCK 2
#define DLM_USER_QUERY 3
#define DLM_USER_CREATE_LOCKSPACE 4
#define DLM_USER_REMOVE_LOCKSPACE 5
#define DLM_USER_PURGE 6
#define DLM_USER_DEADLOCK 7
/* Lockspace flags */
#define DLM_USER_LSFLG_AUTOFREE 1
#define DLM_USER_LSFLG_FORCEFREE 2
#endif