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vfio-pci: Use mutex around open, release, and remove

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Serializing open/release allows us to fix a refcnt error if we fail
to enable the device and lets us prevent devices from being unbound
or opened, giving us an opportunity to do bus resets on release.  No
restriction added to serialize binding devices to vfio-pci while the
mutex is held though.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2014-08-07 11:12:04 -06:00
parent 9c22e660ce
commit 61d792562b
2 changed files with 24 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/vfio/pci/vfio_pci.c
View File

@ -37,6 +37,8 @@ module_param_named(nointxmask, nointxmask, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(nointxmask,
"Disable support for PCI 2.3 style INTx masking. If this resolves problems for specific devices, report lspci -vvvxxx to linux-pci@vger.kernel.org so the device can be fixed automatically via the broken_intx_masking flag.");
static DEFINE_MUTEX(driver_lock);
static int vfio_pci_enable(struct vfio_pci_device *vdev)
{
struct pci_dev *pdev = vdev->pdev;
@ -163,23 +165,29 @@ static void vfio_pci_release(void *device_data)
{
struct vfio_pci_device *vdev = device_data;
if (atomic_dec_and_test(&vdev->refcnt)) {
mutex_lock(&driver_lock);
if (!(--vdev->refcnt)) {
vfio_spapr_pci_eeh_release(vdev->pdev);
vfio_pci_disable(vdev);
}
mutex_unlock(&driver_lock);
module_put(THIS_MODULE);
}
static int vfio_pci_open(void *device_data)
{
struct vfio_pci_device *vdev = device_data;
int ret;
int ret = 0;
if (!try_module_get(THIS_MODULE))
return -ENODEV;
if (atomic_inc_return(&vdev->refcnt) == 1) {
mutex_lock(&driver_lock);
if (!vdev->refcnt) {
ret = vfio_pci_enable(vdev);
if (ret)
goto error;
@ -190,9 +198,10 @@ static int vfio_pci_open(void *device_data)
goto error;
}
}
return 0;
vdev->refcnt++;
error:
mutex_unlock(&driver_lock);
if (ret)
module_put(THIS_MODULE);
return ret;
}
@ -849,7 +858,6 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
vdev->irq_type = VFIO_PCI_NUM_IRQS;
mutex_init(&vdev->igate);
spin_lock_init(&vdev->irqlock);
atomic_set(&vdev->refcnt, 0);
ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
if (ret) {
@ -864,14 +872,17 @@ static void vfio_pci_remove(struct pci_dev *pdev)
{
struct vfio_pci_device *vdev;
vdev = vfio_del_group_dev(&pdev->dev);
if (!vdev)
return;
mutex_lock(&driver_lock);
vdev = vfio_del_group_dev(&pdev->dev);
if (vdev) {
iommu_group_put(pdev->dev.iommu_group);
kfree(vdev);
}
mutex_unlock(&driver_lock);
}
static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
pci_channel_state_t state)
{

2
drivers/vfio/pci/vfio_pci_private.h
View File

@ -55,7 +55,7 @@ struct vfio_pci_device {
bool bardirty;
bool has_vga;
struct pci_saved_state *pci_saved_state;
atomic_t refcnt;
int refcnt;
struct eventfd_ctx *err_trigger;
};