Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
Pull vhost fixes from Michael Tsirkin:
"vhost: more fixes for 3.11
This includes some fixes for vhost net and scsi drivers.
The test module has already been reworked to avoid rcu usage, but the
necessary core changes are missing, we fixed this.
Unlikely to affect any real-world users, but it's early in the cycle
so, let's merge them"
(It was earlier when Michael originally sent the email, but it somehot
got missed in the flood, so here it is after -rc2)
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
vhost: Remove custom vhost rcu usage
vhost-scsi: Always access vq->private_data under vq mutex
vhost-net: Always access vq->private_data under vq mutex
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 027be91..969a859 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -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>
@@ -346,12 +345,11 @@
struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
bool zcopy, zcopy_used;
- /* TODO: check that we are running from vhost_worker? */
- sock = rcu_dereference_check(vq->private_data, 1);
- if (!sock)
- return;
-
mutex_lock(&vq->mutex);
+ sock = vq->private_data;
+ if (!sock)
+ goto out;
+
vhost_disable_notify(&net->dev, vq);
hdr_size = nvq->vhost_hlen;
@@ -461,7 +459,7 @@
break;
}
}
-
+out:
mutex_unlock(&vq->mutex);
}
@@ -570,14 +568,14 @@
s16 headcount;
size_t vhost_hlen, sock_hlen;
size_t vhost_len, sock_len;
- /* TODO: check that we are running from vhost_worker? */
- struct socket *sock = rcu_dereference_check(vq->private_data, 1);
-
- if (!sock)
- return;
+ struct socket *sock;
mutex_lock(&vq->mutex);
+ sock = vq->private_data;
+ if (!sock)
+ goto out;
vhost_disable_notify(&net->dev, vq);
+
vhost_hlen = nvq->vhost_hlen;
sock_hlen = nvq->sock_hlen;
@@ -652,7 +650,7 @@
break;
}
}
-
+out:
mutex_unlock(&vq->mutex);
}
@@ -750,8 +748,7 @@
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;
@@ -764,10 +761,9 @@
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;
}
@@ -923,8 +919,7 @@
}
/* 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));
@@ -934,7 +929,7 @@
}
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;
@@ -968,7 +963,7 @@
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);
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 06adf31..0c27c7d 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -902,19 +902,15 @@
int head, ret;
u8 target;
+ mutex_lock(&vq->mutex);
/*
* We can handle the vq only after the endpoint is setup by calling the
* VHOST_SCSI_SET_ENDPOINT ioctl.
- *
- * TODO: Check that we are running from vhost_worker which acts
- * as read-side critical section for vhost kind of RCU.
- * See the comments in struct vhost_virtqueue in drivers/vhost/vhost.h
*/
- vs_tpg = rcu_dereference_check(vq->private_data, 1);
+ vs_tpg = vq->private_data;
if (!vs_tpg)
- return;
+ goto out;
- mutex_lock(&vq->mutex);
vhost_disable_notify(&vs->dev, vq);
for (;;) {
@@ -1064,6 +1060,7 @@
vhost_scsi_free_cmd(cmd);
err_cmd:
vhost_scsi_send_bad_target(vs, vq, head, out);
+out:
mutex_unlock(&vq->mutex);
}
@@ -1232,9 +1229,8 @@
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);
}
@@ -1313,9 +1309,8 @@
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);
}
}
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index a73ea21..339eae8 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -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 @@
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]);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 42298cd..4465ed5 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -103,14 +103,8 @@
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;
