[PATCH] Cleanup of MSI code

[Neil Turton <nturton@solarflare.com>]

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A few cleanups of the MSI code.  There were a couple of race conditions
in the use of msi_dev_head which this patch fixes.  Use list_empty
rather than list_empty_careful since pirq_list_head is only ever
accessed under pirq_list_lock.  I removed some unused variables.

Signed-off-by: Neil Turton <nturton@solarflare.com>



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diff -r 0da2e3c3ae18 -r e48832688d07 drivers/pci/msi-xen.c
--- a/drivers/pci/msi-xen.c	Thu May 08 13:44:57 2008 +0100
+++ b/drivers/pci/msi-xen.c	Fri May 09 14:13:44 2008 +0100
@@ -32,7 +32,7 @@ int msi_register(struct msi_ops *ops)
 	return 0;
 }
 
-static struct list_head msi_dev_head;
+static LIST_HEAD(msi_dev_head);
 static int msi_dev_head_inited = 0;
 DEFINE_SPINLOCK(msi_dev_lock);
 
@@ -54,11 +54,6 @@ static struct msi_dev_list *get_msi_dev_
 	struct msi_dev_list *msi_dev_list, *ret = NULL;
 	unsigned long flags;
 
-	if (!msi_dev_head_inited) {
-		INIT_LIST_HEAD(&msi_dev_head);
-		msi_dev_head_inited = 1;
-	}
-
 	spin_lock_irqsave(&msi_dev_lock, flags);
 
 	list_for_each_entry(msi_dev_list, &msi_dev_head, list)
@@ -79,10 +74,10 @@ static struct msi_dev_list *get_msi_dev_
 		return NULL;
 	}
 
+	spin_lock_init(&ret->pirq_list_lock);
+	INIT_LIST_HEAD(&ret->pirq_list_head);
 	list_add_tail(&ret->list, &msi_dev_head);
 	spin_unlock_irqrestore(&msi_dev_lock, flags);
-	spin_lock_init(&ret->pirq_list_lock);
-	INIT_LIST_HEAD(&ret->pirq_list_head);
 	return ret;
 }
 
@@ -304,10 +299,9 @@ int pci_save_msix_state(struct pci_dev *
 	msi_dev_entry = get_msi_dev_pirq_list(dev);
 
 	spin_lock_irqsave(&msi_dev_entry->pirq_list_lock, flags);
-	if (!list_empty_careful(&msi_dev_entry->pirq_list_head))
-		list_for_each_entry_safe(pirq_entry, tmp,
-		                         &msi_dev_entry->pirq_list_head, list)
-			msi_unmap_pirq(dev, pirq_entry->pirq);
+        list_for_each_entry_safe(pirq_entry, tmp,
+                                 &msi_dev_entry->pirq_list_head, list)
+		msi_unmap_pirq(dev, pirq_entry->pirq);
 	spin_unlock_irqrestore(&msi_dev_entry->pirq_list_lock, flags);
 
 	disable_msi_mode(dev, pos, PCI_CAP_ID_MSIX);
@@ -394,7 +388,7 @@ static int msix_capability_init(struct p
 		return -ENOMEM;
 
 	spin_lock_irqsave(&msi_dev_entry->pirq_list_lock, flags);
-	if (!list_empty_careful(&msi_dev_entry->pirq_list_head))
+	if (!list_empty(&msi_dev_entry->pirq_list_head))
 	{
 		printk(KERN_WARNING "msix pirqs for dev %02x:%02x:%01x are not freed \
 		       before acquire again.\n", dev->bus->number, PCI_SLOT(dev->devfn),
@@ -678,7 +672,7 @@ void msi_remove_pci_irq_vectors(struct p
 	msi_dev_entry = get_msi_dev_pirq_list(dev);
 
 	spin_lock_irqsave(&msi_dev_entry->pirq_list_lock, flags);
-	if (!list_empty_careful(&msi_dev_entry->pirq_list_head))
+	if (!list_empty(&msi_dev_entry->pirq_list_head))
 	{
 		printk(KERN_WARNING "msix pirqs for dev %02x:%02x:%01x are not freed \
 		       before acquire again.\n", dev->bus->number, PCI_SLOT(dev->devfn),
diff -r 0da2e3c3ae18 -r e48832688d07 drivers/xen/pciback/conf_space_capability_msi.c
--- a/drivers/xen/pciback/conf_space_capability_msi.c	Thu May 08 13:44:57 2008 +0100
+++ b/drivers/xen/pciback/conf_space_capability_msi.c	Fri May 09 14:13:44 2008 +0100
@@ -11,7 +11,6 @@ int pciback_enable_msi(struct pciback_de
 		struct pci_dev *dev, struct xen_pci_op *op)
 {
 	int otherend = pdev->xdev->otherend_id;
-	int irq;
 	int status;
 
 	status = pci_enable_msi(dev);
@@ -29,8 +28,6 @@ int pciback_disable_msi(struct pciback_d
 int pciback_disable_msi(struct pciback_device *pdev,
 		struct pci_dev *dev, struct xen_pci_op *op)
 {
-	int old_irq = dev->irq;
-
 	pci_disable_msi(dev);
 
 	op->value = dev->irq;
@@ -40,7 +37,7 @@ int pciback_enable_msix(struct pciback_d
 int pciback_enable_msix(struct pciback_device *pdev,
 		struct pci_dev *dev, struct xen_pci_op *op)
 {
-	int otherend = pdev->xdev->otherend_id, result, i;
+	int result;
 
 	result = pci_enable_msix(dev, op->msix_entries, op->value);
 


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