> > > > if (sock == oldsock)
> > > > goto done;
> > > >
> > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > > > index e69d238..fc9bde2 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_assign_pointer(dev->memory, memory);
> > >
> > > This is called when there can be no active readers, so the smp_wmb
> > > inside rcu_assign_pointer isn't really needed.
> > > Use RCU_INIT_POINTER or something like this instead?
> >
> > Good point! Fixed.
> >
> > > > return 0;
> > > > }
> > > >
> > > > @@ -212,8 +212,8 @@ 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_const(dev->memory));
> >
> > kfree(rcu_dereference_protected(dev->memory,
> > lockdep_is_held(&dev->mutex));
> >
> > > > + rcu_assign_pointer(dev->memory, NULL);
> > >
> > > Same here.
> >
> > Fixed -- any in any case, we can always use RCU_INIT_POINTER() when
> > assigning NULL.
> >
> > > > if (dev->mm)
> > > > mmput(dev->mm);
> > > > dev->mm = NULL;
> > > > @@ -294,14 +294,14 @@ 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_const(dev->memory), 1);
> >
> > return memory_access_ok(dev, rcu_dereference_protected(dev->memory, lockdep_is_held(&dev->mutex)), 1);
> >
> > And yes, we do need an rcu_dereference_vqdev() wrapper function, but just
> > want to identify the mutexes for the moment.
> >
> > Maybe a separate rcu_dereference_vq() as well -- but you tell me!
> >
> > > > }
> > > >
> > > > /* 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(vq->dev->memory),
> > >
> > > rcu_dereference_const. This is called under vq mutex and the comment
> > > above it says as much.
> >
> > return memory_access_ok(dev, rcu_dereference_protected(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 +342,7 @@ 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_const(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
> --
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