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ipc,shm: introduce shmctl_nolock

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Similar to semctl and msgctl, when calling msgctl, the *_INFO and *_STAT
commands can be performed without acquiring the ipc object.

Add a shmctl_nolock() function and move the logic of *_INFO and *_STAT out
of msgctl().  Since we are just moving functionality, this change still
takes the lock and it will be properly lockless in the next patch.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Rik van Riel <riel@redhat.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>
This commit is contained in:
Davidlohr Bueso 2013-09-11 14:26:18 -07:00 committed by Linus Torvalds
parent 3b1c4ad377
commit 68eccc1dc3
1 changed files with 41 additions and 20 deletions
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61
ipc/shm.c
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@ -820,28 +820,23 @@ out_up:
return err; return err;
} }
SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf) static int shmctl_nolock(struct ipc_namespace *ns, int shmid,
int cmd, int version, void __user *buf)
{ {
int err;
struct shmid_kernel *shp; struct shmid_kernel *shp;
int err, version;
struct ipc_namespace *ns;
if (cmd < 0 || shmid < 0) {
err = -EINVAL;
goto out;
}
version = ipc_parse_version(&cmd);
ns = current->nsproxy->ipc_ns;
switch (cmd) { /* replace with proc interface ? */
case IPC_INFO:
{
struct shminfo64 shminfo;
/* preliminary security checks for *_INFO */
if (cmd == IPC_INFO || cmd == SHM_INFO) {
err = security_shm_shmctl(NULL, cmd); err = security_shm_shmctl(NULL, cmd);
if (err) if (err)
return err; return err;
}
switch (cmd) {
case IPC_INFO:
{
struct shminfo64 shminfo;
memset(&shminfo, 0, sizeof(shminfo)); memset(&shminfo, 0, sizeof(shminfo));
shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni; shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
@ -864,10 +859,6 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
{ {
struct shm_info shm_info; struct shm_info shm_info;
err = security_shm_shmctl(NULL, cmd);
if (err)
return err;
memset(&shm_info, 0, sizeof(shm_info)); memset(&shm_info, 0, sizeof(shm_info));
down_read(&shm_ids(ns).rw_mutex); down_read(&shm_ids(ns).rw_mutex);
shm_info.used_ids = shm_ids(ns).in_use; shm_info.used_ids = shm_ids(ns).in_use;
@ -928,6 +919,36 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
err = result; err = result;
goto out; goto out;
} }
default:
return -EINVAL;
}
out_unlock:
shm_unlock(shp);
out:
return err;
}
SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
{
struct shmid_kernel *shp;
int err, version;
struct ipc_namespace *ns;
if (cmd < 0 || shmid < 0) {
err = -EINVAL;
goto out;
}
version = ipc_parse_version(&cmd);
ns = current->nsproxy->ipc_ns;
switch (cmd) {
case IPC_INFO:
case SHM_INFO:
case SHM_STAT:
case IPC_STAT:
return shmctl_nolock(ns, shmid, cmd, version, buf);
case SHM_LOCK: case SHM_LOCK:
case SHM_UNLOCK: case SHM_UNLOCK:
{ {