Commit 22fa90c7 authored by Asias He's avatar Asias He Committed by Michael S. Tsirkin
Browse files

vhost: Remove custom vhost rcu usage 



Now, vq->private_data is always accessed under vq mutex. No need to play
the vhost rcu trick.

Signed-off-by: default avatarAsias He <asias@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent e7802212

drivers/vhost/net.c

+6 −10
Original line number Diff line number Diff line
@@ -15,7 +15,6 @@ 
#include <linux/moduleparam.h>

#include <linux/mutex.h>

#include <linux/workqueue.h>

#include <linux/rcupdate.h>

#include <linux/file.h>

#include <linux/slab.h>
@@ -749,8 +748,7 @@ static int vhost_net_enable_vq(struct vhost_net *n, 
	struct vhost_poll *poll = n->poll + (nvq - n->vqs);

	struct socket *sock;



	sock = rcu_dereference_protected(vq->private_data,

					 lockdep_is_held(&vq->mutex));

	sock = vq->private_data;

	if (!sock)

		return 0;
@@ -763,10 +761,9 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n, 
	struct socket *sock;



	mutex_lock(&vq->mutex);

	sock = rcu_dereference_protected(vq->private_data,

					 lockdep_is_held(&vq->mutex));

	sock = vq->private_data;

	vhost_net_disable_vq(n, vq);

	rcu_assign_pointer(vq->private_data, NULL);

	vq->private_data = NULL;

	mutex_unlock(&vq->mutex);

	return sock;

}
@@ -922,8 +919,7 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd) 
	}



	/* start polling new socket */

	oldsock = rcu_dereference_protected(vq->private_data,

					    lockdep_is_held(&vq->mutex));

	oldsock = vq->private_data;

	if (sock != oldsock) {

		ubufs = vhost_net_ubuf_alloc(vq,

					     sock && vhost_sock_zcopy(sock));
@@ -933,7 +929,7 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd) 
		}



		vhost_net_disable_vq(n, vq);

		rcu_assign_pointer(vq->private_data, sock);

		vq->private_data = sock;

		r = vhost_init_used(vq);

		if (r)

			goto err_used;
@@ -967,7 +963,7 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd) 
	return 0;



err_used:

	rcu_assign_pointer(vq->private_data, oldsock);

	vq->private_data = oldsock;

	vhost_net_enable_vq(n, vq);

	if (ubufs)

		vhost_net_ubuf_put_wait_and_free(ubufs);

drivers/vhost/scsi.c

+2 −4
Original line number Diff line number Diff line
@@ -1223,9 +1223,8 @@ vhost_scsi_set_endpoint(struct vhost_scsi *vs, 
		       sizeof(vs->vs_vhost_wwpn));

		for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {

			vq = &vs->vqs[i].vq;

			/* Flushing the vhost_work acts as synchronize_rcu */

			mutex_lock(&vq->mutex);

			rcu_assign_pointer(vq->private_data, vs_tpg);

			vq->private_data = vs_tpg;

			vhost_init_used(vq);

			mutex_unlock(&vq->mutex);

		}
@@ -1304,9 +1303,8 @@ vhost_scsi_clear_endpoint(struct vhost_scsi *vs, 
	if (match) {

		for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {

			vq = &vs->vqs[i].vq;

			/* Flushing the vhost_work acts as synchronize_rcu */

			mutex_lock(&vq->mutex);

			rcu_assign_pointer(vq->private_data, NULL);

			vq->private_data = NULL;

			mutex_unlock(&vq->mutex);

		}

	}

drivers/vhost/test.c

+2 −4
Original line number Diff line number Diff line
@@ -13,7 +13,6 @@ 
#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/workqueue.h>

#include <linux/rcupdate.h>

#include <linux/file.h>

#include <linux/slab.h>
@@ -200,9 +199,8 @@ static long vhost_test_run(struct vhost_test *n, int test) 
		priv = test ? n : NULL;



		/* start polling new socket */

		oldpriv = rcu_dereference_protected(vq->private_data,

						    lockdep_is_held(&vq->mutex));

		rcu_assign_pointer(vq->private_data, priv);

		oldpriv = vq->private_data;

		vq->private_data = priv;



		r = vhost_init_used(&n->vqs[index]);

drivers/vhost/vhost.h

+2 −8
Original line number Diff line number Diff line
@@ -103,14 +103,8 @@ struct vhost_virtqueue { 
	struct iovec iov[UIO_MAXIOV];

	struct iovec *indirect;

	struct vring_used_elem *heads;

	/* We use a kind of RCU to access private pointer.

	 * All readers access it from worker, which makes it possible to

	 * flush the vhost_work instead of synchronize_rcu. Therefore readers do

	 * not need to call rcu_read_lock/rcu_read_unlock: the beginning of

	 * vhost_work execution acts instead of rcu_read_lock() and the end of

	 * vhost_work execution acts instead of rcu_read_unlock().

	 * Writers use virtqueue mutex. */

	void __rcu *private_data;

	/* Protected by virtqueue mutex. */

	void *private_data;

	/* Log write descriptors */

	void __user *log_base;

	struct vhost_log *log;