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vfio: Use down_reads to protect iommu disconnects 

If a group or device is released or a container is unset from a group
it can race against file ops on the container.  Protect these with
down_reads to allow concurrent users.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reported-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alex Williamson 2013-04-29 08:41:36 -06:00
parent 9587f44aa6
commit 0b43c08233
1 changed files with 46 additions and 16 deletions
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62
drivers/vfio/vfio.c
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@ -704,9 +704,13 @@ EXPORT_SYMBOL_GPL(vfio_del_group_dev);
static long vfio_ioctl_check_extension(struct vfio_container *container,
unsigned long arg)
{
struct vfio_iommu_driver *driver = container->iommu_driver;
struct vfio_iommu_driver *driver;
long ret = 0;
down_read(&container->group_lock);
driver = container->iommu_driver;
switch (arg) {
/* No base extensions yet */
default:
@ -736,6 +740,8 @@ static long vfio_ioctl_check_extension(struct vfio_container *container,
VFIO_CHECK_EXTENSION, arg);
}
up_read(&container->group_lock);
return ret;
}
@ -844,9 +850,6 @@ static long vfio_fops_unl_ioctl(struct file *filep,
if (!container)
return ret;
driver = container->iommu_driver;
data = container->iommu_data;
switch (cmd) {
case VFIO_GET_API_VERSION:
ret = VFIO_API_VERSION;
@ -858,8 +861,15 @@ static long vfio_fops_unl_ioctl(struct file *filep,
ret = vfio_ioctl_set_iommu(container, arg);
break;
default:
down_read(&container->group_lock);
driver = container->iommu_driver;
data = container->iommu_data;
if (driver) /* passthrough all unrecognized ioctls */
ret = driver->ops->ioctl(data, cmd, arg);
up_read(&container->group_lock);
}
return ret;
@ -910,35 +920,55 @@ static ssize_t vfio_fops_read(struct file *filep, char __user *buf,
size_t count, loff_t *ppos)
{
struct vfio_container *container = filep->private_data;
struct vfio_iommu_driver *driver = container->iommu_driver;
struct vfio_iommu_driver *driver;
ssize_t ret = -EINVAL;
if (unlikely(!driver || !driver->ops->read))
return -EINVAL;
down_read(&container->group_lock);
return driver->ops->read(container->iommu_data, buf, count, ppos);
driver = container->iommu_driver;
if (likely(driver && driver->ops->read))
ret = driver->ops->read(container->iommu_data,
buf, count, ppos);
up_read(&container->group_lock);
return ret;
}
static ssize_t vfio_fops_write(struct file *filep, const char __user *buf,
size_t count, loff_t *ppos)
{
struct vfio_container *container = filep->private_data;
struct vfio_iommu_driver *driver = container->iommu_driver;
struct vfio_iommu_driver *driver;
ssize_t ret = -EINVAL;
if (unlikely(!driver || !driver->ops->write))
return -EINVAL;
down_read(&container->group_lock);
return driver->ops->write(container->iommu_data, buf, count, ppos);
driver = container->iommu_driver;
if (likely(driver && driver->ops->write))
ret = driver->ops->write(container->iommu_data,
buf, count, ppos);
up_read(&container->group_lock);
return ret;
}
static int vfio_fops_mmap(struct file *filep, struct vm_area_struct *vma)
{
struct vfio_container *container = filep->private_data;
struct vfio_iommu_driver *driver = container->iommu_driver;
struct vfio_iommu_driver *driver;
int ret = -EINVAL;
if (unlikely(!driver || !driver->ops->mmap))
return -EINVAL;
down_read(&container->group_lock);
return driver->ops->mmap(container->iommu_data, vma);
driver = container->iommu_driver;
if (likely(driver && driver->ops->mmap))
ret = driver->ops->mmap(container->iommu_data, vma);
up_read(&container->group_lock);
return ret;
}
static const struct file_operations vfio_fops = {