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Use a unit number allocator to provide suitable st_dev and st_ino values

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for POSIX shared memory descriptors.  The implementation is similar to
that used for pipes.

MFC after:	1 week
This commit is contained in:
John Baldwin 2014-08-29 18:18:29 +00:00
parent ea463f2dc0
commit 610a2b3c45
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=270823
1 changed files with 19 additions and 2 deletions
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21
sys/kern/uipc_shm.c
View file

@ -49,6 +49,7 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
@ -101,6 +102,8 @@ static LIST_HEAD(, shm_mapping) *shm_dictionary;
static struct sx shm_dict_lock;
static struct mtx shm_timestamp_lock;
static u_long shm_hash;
static struct unrhdr *shm_ino_unr;
static dev_t shm_dev_ino;
#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
@ -408,6 +411,8 @@ shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
sb->st_uid = shmfd->shm_uid;
sb->st_gid = shmfd->shm_gid;
mtx_unlock(&shm_timestamp_lock);
sb->st_dev = shm_dev_ino;
sb->st_ino = shmfd->shm_ino;
return (0);
}
@ -539,6 +544,7 @@ static struct shmfd *
shm_alloc(struct ucred *ucred, mode_t mode)
{
struct shmfd *shmfd;
int ino;
shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
shmfd->shm_size = 0;
@ -555,6 +561,11 @@ shm_alloc(struct ucred *ucred, mode_t mode)
vfs_timestamp(&shmfd->shm_birthtime);
shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
shmfd->shm_birthtime;
ino = alloc_unr(shm_ino_unr);
if (ino == -1)
shmfd->shm_ino = 0;
else
shmfd->shm_ino = ino;
refcount_init(&shmfd->shm_refs, 1);
mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
rangelock_init(&shmfd->shm_rl);
@ -585,6 +596,8 @@ shm_drop(struct shmfd *shmfd)
rangelock_destroy(&shmfd->shm_rl);
mtx_destroy(&shmfd->shm_mtx);
vm_object_deallocate(shmfd->shm_object);
if (shmfd->shm_ino != 0)
free_unr(shm_ino_unr, shmfd->shm_ino);
free(shmfd, M_SHMFD);
}
}
@ -617,14 +630,18 @@ shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
* the mappings in a hash table.
*/
static void
shm_dict_init(void *arg)
shm_init(void *arg)
{
mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
sx_init(&shm_dict_lock, "shm dictionary");
shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
shm_ino_unr = new_unrhdr(1, INT32_MAX, NULL);
KASSERT(shm_ino_unr != NULL, ("shm fake inodes not initialized"));
shm_dev_ino = devfs_alloc_cdp_inode();
KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
}
SYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL);
SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
static struct shmfd *
shm_lookup(char *path, Fnv32_t fnv)