Messages in this thread | | | Date | Wed, 5 May 2010 00:39:36 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH tip/core/rcu 43/48] vhost: add __rcu annotations |
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On Tue, May 04, 2010 at 01:19:53PM -0700, Paul E. McKenney wrote: > From: Arnd Bergmann <arnd@relay.de.ibm.com> > > 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 | 6 +++--- > drivers/vhost/vhost.c | 12 ++++++------ > drivers/vhost/vhost.h | 4 ++-- > 3 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index 9777583..36e8dec 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -364,7 +364,7 @@ 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 = rcu_dereference(vq->private_data);
This should be rcu_dereference_const as well: it is called with vq mutex held.
> if (!sock) > return; > if (vq == n->vqs + VHOST_NET_VQ_TX) { > @@ -380,7 +380,7 @@ 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_const(vq->private_data); > vhost_net_disable_vq(n, vq); > rcu_assign_pointer(vq->private_data, NULL); > mutex_unlock(&vq->mutex); > @@ -518,7 +518,7 @@ 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_const(vq->private_data); > 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?
> 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)); > + rcu_assign_pointer(dev->memory, NULL);
Same here.
> 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); > } > > /* 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.
> 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); > 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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