[RFC PATCH v6 17/20] vfio: add local lock in virqfd instead of depending on VFIO PCI

Antonios Motakis
2014-06-05T17:06:05Z

Sharing the same spinlock with the VFIO bus driver is not necessary for
the virqfd code, so remove that dependency.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
---
drivers/vfio/pci/vfio_pci_intrs.c | 10 +++++-----
drivers/vfio/virqfd.c | 24 +++++++++++++-----------
include/linux/vfio.h | 3 +--
3 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 3f909bb..e56c814 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -226,8 +226,8 @@ static int vfio_intx_set_signal(struct vfio_pci_device *vdev, int fd)
static void vfio_intx_disable(struct vfio_pci_device *vdev)
{
vfio_intx_set_signal(vdev, -1);
- virqfd_disable(vdev, &vdev->ctx[0].unmask);
- virqfd_disable(vdev, &vdev->ctx[0].mask);
+ virqfd_disable(&vdev->ctx[0].unmask);
+ virqfd_disable(&vdev->ctx[0].mask);
vdev->irq_type = VFIO_PCI_NUM_IRQS;
vdev->num_ctx = 0;
kfree(vdev->ctx);
@@ -377,8 +377,8 @@ static void vfio_msi_disable(struct vfio_pci_device *vdev, bool msix)
vfio_msi_set_block(vdev, 0, vdev->num_ctx, NULL, msix);

for (i = 0; i < vdev->num_ctx; i++) {
- virqfd_disable(vdev, &vdev->ctx[i].unmask);
- virqfd_disable(vdev, &vdev->ctx[i].mask);
+ virqfd_disable(&vdev->ctx[i].unmask);
+ virqfd_disable(&vdev->ctx[i].mask);
}

if (msix) {
@@ -415,7 +415,7 @@ static int vfio_pci_set_intx_unmask(struct vfio_pci_device *vdev,
vfio_send_intx_eventfd, NULL,
&vdev->ctx[0].unmask, fd);

- virqfd_disable(vdev, &vdev->ctx[0].unmask);
+ virqfd_disable(&vdev->ctx[0].unmask);
}

return 0;
diff --git a/drivers/vfio/virqfd.c b/drivers/vfio/virqfd.c
index 9cf2842..4528450 100644
--- a/drivers/vfio/virqfd.c
+++ b/drivers/vfio/virqfd.c
@@ -17,6 +17,7 @@
#include "pci/vfio_pci_private.h"

static struct workqueue_struct *vfio_irqfd_cleanup_wq;
+static spinlock_t lock;

int __init vfio_pci_virqfd_init(void)
{
@@ -25,6 +26,8 @@ int __init vfio_pci_virqfd_init(void)
if (!vfio_irqfd_cleanup_wq)
return -ENOMEM;

+ spin_lock_init(&lock);
+
return 0;
}

@@ -53,21 +56,21 @@ static int virqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)

if (flags & POLLHUP) {
unsigned long flags;
- spin_lock_irqsave(&virqfd->vdev->irqlock, flags);
+ spin_lock_irqsave(&lock, flags);

/*
* The eventfd is closing, if the virqfd has not yet been
* queued for release, as determined by testing whether the
- * vdev pointer to it is still valid, queue it now. As
+ * virqfd pointer to it is still valid, queue it now. As
* with kvm irqfds, we know we won't race against the virqfd
- * going away because we hold wqh->lock to get here.
+ * going away because we hold the lock to get here.
*/
if (*(virqfd->pvirqfd) == virqfd) {
*(virqfd->pvirqfd) = NULL;
virqfd_deactivate(virqfd);
}

- spin_unlock_irqrestore(&virqfd->vdev->irqlock, flags);
+ spin_unlock_irqrestore(&lock, flags);
}

return 0;
@@ -143,16 +146,16 @@ int virqfd_enable(struct vfio_pci_device *vdev,
* we update the pointer to the virqfd under lock to avoid
* pushing multiple jobs to release the same virqfd.
*/
- spin_lock_irq(&vdev->irqlock);
+ spin_lock_irq(&lock);

if (*pvirqfd) {
- spin_unlock_irq(&vdev->irqlock);
+ spin_unlock_irq(&lock);
ret = -EBUSY;
goto err_busy;
}
*pvirqfd = virqfd;

- spin_unlock_irq(&vdev->irqlock);
+ spin_unlock_irq(&lock);

/*
* Install our own custom wake-up handling so we are notified via
@@ -189,19 +192,18 @@ err_fd:
return ret;
}

-void virqfd_disable(struct vfio_pci_device *vdev,
- struct virqfd **pvirqfd)
+void virqfd_disable(struct virqfd **pvirqfd)
{
unsigned long flags;

- spin_lock_irqsave(&vdev->irqlock, flags);
+ spin_lock_irqsave(&lock, flags);

if (*pvirqfd) {
virqfd_deactivate(*pvirqfd);
*pvirqfd = NULL;
}

- spin_unlock_irqrestore(&vdev->irqlock, flags);
+ spin_unlock_irqrestore(&lock, flags);

/*
* Block until we know all outstanding shutdown jobs have completed.
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 43968e8..44c9808 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -123,7 +123,6 @@ extern int virqfd_enable(struct vfio_pci_device *vdev,
int (*handler)(struct vfio_pci_device *, void *),
void (*thread)(struct vfio_pci_device *, void *),
void *data, struct virqfd **pvirqfd, int fd);
-extern void virqfd_disable(struct vfio_pci_device *vdev,
- struct virqfd **pvirqfd);
+extern void virqfd_disable(struct virqfd **pvirqfd);

#endif /* VFIO_H */
--
1.8.3.2