vhost: add __rcu annotations

Also add rcu_dereference_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>

3 files changed, 35 insertions, 13 deletions

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 29e850a7a2f9..1318ee008346 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -127,7 +127,10 @@ static void handle_tx(struct vhost_net *net)
         size_t len, total_len = 0;
         int err, wmem;
         size_t hdr_size;
-        struct socket *sock = rcu_dereference(vq->private_data);
+        struct socket *sock;
+
+        sock = rcu_dereference_check(vq->private_data,
+                                     lockdep_is_held(&vq->mutex));
         if (!sock)
                 return;
 
@@ -582,7 +585,10 @@ 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) {
@@ -598,7 +604,8 @@ 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);
@@ -736,7 +743,8 @@ 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) {
                 vhost_net_disable_vq(n, vq);
                 rcu_assign_pointer(vq->private_data, sock);
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index e05557d52999..b5c49478d203 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -284,7 +284,7 @@ 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;
 }
 
@@ -316,8 +316,9 @@ 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;
@@ -401,14 +402,22 @@ 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);
+        struct vhost_memory *mp;
+
+        mp = rcu_dereference_protected(dev->memory,
+                                       lockdep_is_held(&dev->mutex));
+        return memory_access_ok(dev, mp, 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,
+        struct vhost_memory *mp;
+
+        mp = rcu_dereference_protected(vq->dev->memory,
+                                       lockdep_is_held(&vq->mutex));
+        return vq_memory_access_ok(log_base, mp,
                             vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
                 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
                                         sizeof *vq->used +
@@ -448,7 +457,8 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
                 kfree(newmem);
                 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 afd77295971c..af3c11ded5fd 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -106,7 +106,7 @@ struct vhost_virtqueue {
          * vhost_work execution acts instead of rcu_read_lock() and the end of
          * vhost_work 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];
@@ -116,7 +116,7 @@ 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;
@@ -173,7 +173,11 @@ enum {
 
 static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
 {
-        unsigned acked_features = rcu_dereference(dev->acked_features);
+        unsigned acked_features;
+
+        acked_features =
+                rcu_dereference_index_check(dev->acked_features,
+                                            lockdep_is_held(&dev->mutex));
         return acked_features & (1 << bit);
 }