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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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