linux-stable/include/uapi/linux/shm.h
Davidlohr Bueso f57a19a7bc ipc,shm: document new limits in the uapi header
This is useful in the future and allows users to better understand the
reasoning behind the changes.

Also use UL as we're dealing with it anyways.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 16:08:14 -07:00

80 lines
2.6 KiB
C

#ifndef _UAPI_LINUX_SHM_H_
#define _UAPI_LINUX_SHM_H_
#include <linux/ipc.h>
#include <linux/errno.h>
#ifndef __KERNEL__
#include <unistd.h>
#endif
/*
* SHMMNI, SHMMAX and SHMALL are default upper limits which can be
* modified by sysctl. The SHMMAX and SHMALL values have been chosen to
* be as large possible without facilitating scenarios where userspace
* causes overflows when adjusting the limits via operations of the form
* "retrieve current limit; add X; update limit". It is therefore not
* advised to make SHMMAX and SHMALL any larger. These limits are
* suitable for both 32 and 64-bit systems.
*/
#define SHMMIN 1 /* min shared seg size (bytes) */
#define SHMMNI 4096 /* max num of segs system wide */
#define SHMMAX (ULONG_MAX - (1UL << 24)) /* max shared seg size (bytes) */
#define SHMALL (ULONG_MAX - (1UL << 24)) /* max shm system wide (pages) */
#define SHMSEG SHMMNI /* max shared segs per process */
/* Obsolete, used only for backwards compatibility and libc5 compiles */
struct shmid_ds {
struct ipc_perm shm_perm; /* operation perms */
int shm_segsz; /* size of segment (bytes) */
__kernel_time_t shm_atime; /* last attach time */
__kernel_time_t shm_dtime; /* last detach time */
__kernel_time_t shm_ctime; /* last change time */
__kernel_ipc_pid_t shm_cpid; /* pid of creator */
__kernel_ipc_pid_t shm_lpid; /* pid of last operator */
unsigned short shm_nattch; /* no. of current attaches */
unsigned short shm_unused; /* compatibility */
void *shm_unused2; /* ditto - used by DIPC */
void *shm_unused3; /* unused */
};
/* Include the definition of shmid64_ds and shminfo64 */
#include <asm/shmbuf.h>
/* permission flag for shmget */
#define SHM_R 0400 /* or S_IRUGO from <linux/stat.h> */
#define SHM_W 0200 /* or S_IWUGO from <linux/stat.h> */
/* mode for attach */
#define SHM_RDONLY 010000 /* read-only access */
#define SHM_RND 020000 /* round attach address to SHMLBA boundary */
#define SHM_REMAP 040000 /* take-over region on attach */
#define SHM_EXEC 0100000 /* execution access */
/* super user shmctl commands */
#define SHM_LOCK 11
#define SHM_UNLOCK 12
/* ipcs ctl commands */
#define SHM_STAT 13
#define SHM_INFO 14
/* Obsolete, used only for backwards compatibility */
struct shminfo {
int shmmax;
int shmmin;
int shmmni;
int shmseg;
int shmall;
};
struct shm_info {
int used_ids;
__kernel_ulong_t shm_tot; /* total allocated shm */
__kernel_ulong_t shm_rss; /* total resident shm */
__kernel_ulong_t shm_swp; /* total swapped shm */
__kernel_ulong_t swap_attempts;
__kernel_ulong_t swap_successes;
};
#endif /* _UAPI_LINUX_SHM_H_ */