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>

1 files changed, 16 insertions, 6 deletions

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);