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Date:	Thu,  5 Jun 2014 19:03:25 +0200
From:	Antonios Motakis <a.motakis@...tualopensystems.com>
To:	alex.williamson@...hat.com, kvmarm@...ts.cs.columbia.edu,
	iommu@...ts.linux-foundation.org
Cc:	tech@...tualopensystems.com, a.rigo@...tualopensystems.com,
	kvm@...r.kernel.org, christoffer.dall@...aro.org,
	will.deacon@....com, kim.phillips@...escale.com,
	stuart.yoder@...escale.com, eric.auger@...aro.org,
	Antonios Motakis <a.motakis@...tualopensystems.com>,
	Alexander Gordeev <agordeev@...hat.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-kernel@...r.kernel.org (open list)
Subject: [RFC PATCH v6 17/20] vfio: add local lock in virqfd instead of depending on VFIO PCI

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@...tualopensystems.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

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