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Add shmatt_t.

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It looks like our "struct shmid_ds::shm_nattch" deviates from the
standard in the sense that it is a signed integer, whereas POSIX
requires that it is unsigned, having a special type shmatt_t.

Patch up our native and 32-bit copies to use a new shmatt_t that is an
unsigned integer. As it's unsigned, we can relax the comparisons that
are performed on it. Leave the Linux, iBCS2, etc. copies of the
structure alone.

Reviewed by:	ngie
Differential Revision:	https://reviews.freebsd.org/D6655
This commit is contained in:
ed 2016-07-26 17:23:49 +00:00
parent a27fa34137
commit 1fc7f43ffa
3 changed files with 6 additions and 4 deletions
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2
sys/compat/freebsd32/freebsd32_ipc.h
View File

@ -72,7 +72,7 @@ struct shmid_ds32 {
int32_t shm_segsz;
pid_t shm_lpid;
pid_t shm_cpid;
int shm_nattch;
unsigned int shm_nattch;
int32_t shm_atime;
int32_t shm_dtime;
int32_t shm_ctime;

4
sys/kern/sysv_shm.c
View File

@ -275,7 +275,7 @@ shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
return (EINVAL);
shmmap_s->shmid = -1;
shmseg->u.shm_dtime = time_second;
if ((--shmseg->u.shm_nattch <= 0) &&
if (--shmseg->u.shm_nattch == 0 &&
(shmseg->u.shm_perm.mode & SHMSEG_REMOVED)) {
shm_deallocate_segment(shmseg);
shm_last_free = segnum;
@ -289,7 +289,7 @@ shm_remove(struct shmid_kernel *shmseg, int segnum)
shmseg->u.shm_perm.key = IPC_PRIVATE;
shmseg->u.shm_perm.mode |= SHMSEG_REMOVED;
if (shmseg->u.shm_nattch <= 0) {
if (shmseg->u.shm_nattch == 0) {
shm_deallocate_segment(shmseg);
shm_last_free = segnum;
}

4
sys/sys/shm.h
View File

@ -92,12 +92,14 @@ struct shmid_ds_old {
};
#endif
typedef unsigned int shmatt_t;
struct shmid_ds {
struct ipc_perm shm_perm; /* operation permission structure */
size_t shm_segsz; /* size of segment in bytes */
pid_t shm_lpid; /* process ID of last shared memory op */
pid_t shm_cpid; /* process ID of creator */
int shm_nattch; /* number of current attaches */
shmatt_t shm_nattch; /* number of current attaches */
time_t shm_atime; /* time of last shmat() */
time_t shm_dtime; /* time of last shmdt() */
time_t shm_ctime; /* time of last change by shmctl() */