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Subject[PATCH RFC tip/core/rcu 23/23] vhost: add __rcu annotations
Date
From: Arnd Bergmann <arnd@relay.de.ibm.com>

Also add rcu_dreference_protected() for code paths where locks are held.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
---
drivers/vhost/net.c | 11 ++++++++---
drivers/vhost/vhost.c | 14 ++++++++------
drivers/vhost/vhost.h | 4 ++--
3 files changed, 18 insertions(+), 11 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 9777583..945c5cb 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -364,7 +364,10 @@ static void vhost_net_disable_vq(struct vhost_net *n,
static void vhost_net_enable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
- struct socket *sock = vq->private_data;
+ struct socket *sock;
+
+ sock = rcu_dereference_protected(vq->private_data,
+ lockdep_is_held(&vq->mutex));
if (!sock)
return;
if (vq == n->vqs + VHOST_NET_VQ_TX) {
@@ -380,7 +383,8 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
struct socket *sock;

mutex_lock(&vq->mutex);
- sock = vq->private_data;
+ sock = rcu_dereference_protected(vq->private_data,
+ lockdep_is_held(&vq->mutex));
vhost_net_disable_vq(n, vq);
rcu_assign_pointer(vq->private_data, NULL);
mutex_unlock(&vq->mutex);
@@ -518,7 +522,8 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
}

/* start polling new socket */
- oldsock = vq->private_data;
+ oldsock = rcu_dereference_protected(vq->private_data,
+ lockdep_is_held(&vq->mutex));
if (sock == oldsock)
goto done;

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index e69d238..fc0c077 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -180,7 +180,7 @@ long vhost_dev_reset_owner(struct vhost_dev *dev)
vhost_dev_cleanup(dev);

memory->nregions = 0;
- dev->memory = memory;
+ RCU_INIT_POINTER(dev->memory, memory);
return 0;
}

@@ -212,8 +212,9 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
fput(dev->log_file);
dev->log_file = NULL;
/* No one will access memory at this point */
- kfree(dev->memory);
- dev->memory = NULL;
+ kfree(rcu_dereference_protected(dev->memory,
+ lockdep_is_held(&dev->mutex)));
+ RCU_INIT_POINTER(dev->memory, NULL);
if (dev->mm)
mmput(dev->mm);
dev->mm = NULL;
@@ -294,14 +295,14 @@ static int vq_access_ok(unsigned int num,
/* Caller should have device mutex but not vq mutex */
int vhost_log_access_ok(struct vhost_dev *dev)
{
- return memory_access_ok(dev, dev->memory, 1);
+ return memory_access_ok(dev, rcu_dereference_protected(dev->memory, lockdep_is_held(&dev->mutex)), 1);
}

/* Verify access for write logging. */
/* Caller should have vq mutex and device mutex */
static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base)
{
- return vq_memory_access_ok(log_base, vq->dev->memory,
+ return vq_memory_access_ok(log_base, rcu_dereference_protected(vq->dev->memory, lockdep_is_held(&dev->mutex)),
vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
(!vq->log_used || log_access_ok(log_base, vq->log_addr,
sizeof *vq->used +
@@ -342,7 +343,8 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)

if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL)))
return -EFAULT;
- oldmem = d->memory;
+ oldmem = rcu_dereference_protected(d->memory,
+ lockdep_is_held(&d->mutex));
rcu_assign_pointer(d->memory, newmem);
synchronize_rcu();
kfree(oldmem);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 44591ba..240396c 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -92,7 +92,7 @@ struct vhost_virtqueue {
* work item execution acts instead of rcu_read_lock() and the end of
* work item execution acts instead of rcu_read_lock().
* Writers use virtqueue mutex. */
- void *private_data;
+ void __rcu *private_data;
/* Log write descriptors */
void __user *log_base;
struct vhost_log log[VHOST_NET_MAX_SG];
@@ -102,7 +102,7 @@ struct vhost_dev {
/* Readers use RCU to access memory table pointer
* log base pointer and features.
* Writers use mutex below.*/
- struct vhost_memory *memory;
+ struct vhost_memory __rcu *memory;
struct mm_struct *mm;
struct mutex mutex;
unsigned acked_features;
--
1.7.0.6


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