Asias He (4): vhost-net: Always access vq->private_data under vq mutex vhost-test: Always access vq->private_data under vq mutex vhost-scsi: Always access vq->private_data under vq mutex vhost: Remove custom vhost rcu usage drivers/vhost/net.c | 37 ++++++++++++++++--------------------- drivers/vhost/scsi.c | 17 ++++++----------- drivers/vhost/test.c | 20 +++++++++----------- drivers/vhost/vhost.h | 10 ++-------- 4 files changed, 33 insertions(+), 51 deletions(-) -- 1.8.1.4
Asias He
2013-May-07 06:54 UTC
[PATCH 1/4] vhost-net: Always access vq->private_data under vq mutex
Signed-off-by: Asias He <asias at redhat.com> --- drivers/vhost/net.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 2b51e23..b616d9a 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -349,12 +349,11 @@ static void handle_tx(struct vhost_net *net) 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); + mutex_lock(&vq->mutex); + sock = vq->private_data; if (!sock) - return; + goto out; - mutex_lock(&vq->mutex); vhost_disable_notify(&net->dev, vq); hdr_size = nvq->vhost_hlen; @@ -463,7 +462,7 @@ static void handle_tx(struct vhost_net *net) break; } } - +out: mutex_unlock(&vq->mutex); } @@ -572,14 +571,14 @@ static void handle_rx(struct vhost_net *net) 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; @@ -654,7 +653,7 @@ static void handle_rx(struct vhost_net *net) break; } } - +out: mutex_unlock(&vq->mutex); } -- 1.8.1.4
Asias He
2013-May-07 06:54 UTC
[PATCH 2/4] vhost-test: Always access vq->private_data under vq mutex
Signed-off-by: Asias He <asias at redhat.com>
---
drivers/vhost/test.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index dc526eb..435b911 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -48,11 +48,12 @@ static void handle_vq(struct vhost_test *n)
size_t len, total_len = 0;
void *private;
- private = rcu_dereference_check(vq->private_data, 1);
- if (!private)
- return;
mutex_lock(&vq->mutex);
+ private = vq->private_data;
+ if (!private)
+ goto out;
+
vhost_disable_notify(&n->dev, vq);
for (;;) {
@@ -89,7 +90,7 @@ static void handle_vq(struct vhost_test *n)
break;
}
}
-
+out:
mutex_unlock(&vq->mutex);
}
--
1.8.1.4
Asias He
2013-May-07 06:54 UTC
[PATCH 3/4] vhost-scsi: Always access vq->private_data under vq mutex
Signed-off-by: Asias He <asias at redhat.com>
---
drivers/vhost/scsi.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 5531ebc..d78768b 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -896,19 +896,15 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct
vhost_virtqueue *vq)
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 (;;) {
@@ -1058,6 +1054,7 @@ err_free:
vhost_scsi_free_cmd(cmd);
err_cmd:
vhost_scsi_send_bad_target(vs, vq, head, out);
+out:
mutex_unlock(&vq->mutex);
}
--
1.8.1.4
Now, vq->private_data is always accessed under vq mutex. No need to play
the vhost rcu trick.
Signed-off-by: Asias He <asias at redhat.com>
---
drivers/vhost/net.c | 16 ++++++----------
drivers/vhost/scsi.c | 6 ++----
drivers/vhost/test.c | 11 ++++-------
drivers/vhost/vhost.h | 10 ++--------
4 files changed, 14 insertions(+), 29 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index b616d9a..05bdc3c 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>
@@ -751,8 +750,7 @@ 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;
@@ -765,10 +763,9 @@ 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;
}
@@ -924,8 +921,7 @@ 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));
@@ -935,7 +931,7 @@ 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;
@@ -969,7 +965,7 @@ 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_and_wait(ubufs);
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index d78768b..de6d817 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -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);
}
}
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index 435b911..5f23477 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>
@@ -139,9 +138,8 @@ static void *vhost_test_stop_vq(struct vhost_test *n,
void *private;
mutex_lock(&vq->mutex);
- private = rcu_dereference_protected(vq->private_data,
- lockdep_is_held(&vq->mutex));
- rcu_assign_pointer(vq->private_data, NULL);
+ private = vq->private_data;
+ vq->private_data = NULL;
mutex_unlock(&vq->mutex);
return private;
}
@@ -205,9 +203,8 @@ 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].vq);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 51aeb5f..2a8c655 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -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;
--
1.8.1.4
On Tue, May 07, 2013 at 02:54:32PM +0800, Asias He wrote:> Asias He (4): > vhost-net: Always access vq->private_data under vq mutex > vhost-test: Always access vq->private_data under vq mutex > vhost-scsi: Always access vq->private_data under vq mutex > vhost: Remove custom vhost rcu usageLooks good, I'll queue this up for 3.11.> drivers/vhost/net.c | 37 ++++++++++++++++--------------------- > drivers/vhost/scsi.c | 17 ++++++----------- > drivers/vhost/test.c | 20 +++++++++----------- > drivers/vhost/vhost.h | 10 ++-------- > 4 files changed, 33 insertions(+), 51 deletions(-) > > -- > 1.8.1.4