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Commit 68eccc1d authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
Browse files

ipc,shm: introduce shmctl_nolock 



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: default avatarDavidlohr Bueso <davidlohr.bueso@hp.com>
Tested-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3b1c4ad3

ipc/shm.c

+39 −18
Original line number Diff line number Diff line
@@ -820,29 +820,24 @@ out_up: 
	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;

	int err, version;

	struct ipc_namespace *ns;



	if (cmd < 0 || shmid < 0) {

		err = -EINVAL;

		goto out;

	/* preliminary security checks for *_INFO */

	if (cmd == IPC_INFO || cmd == SHM_INFO) {

		err = security_shm_shmctl(NULL, cmd);

		if (err)

			return err;

	}



	version = ipc_parse_version(&cmd);

	ns = current->nsproxy->ipc_ns;



	switch (cmd) { /* replace with proc interface ? */

	switch (cmd) {

	case IPC_INFO:

	{

		struct shminfo64 shminfo;



		err = security_shm_shmctl(NULL, cmd);

		if (err)

			return err;



		memset(&shminfo, 0, sizeof(shminfo));

		shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;

		shminfo.shmmax = ns->shm_ctlmax;
@@ -864,10 +859,6 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf) 
	{

		struct shm_info shm_info;



		err = security_shm_shmctl(NULL, cmd);

		if (err)

			return err;



		memset(&shm_info, 0, sizeof(shm_info));

		down_read(&shm_ids(ns).rw_mutex);

		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;

		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_UNLOCK:

	{