From 04df355227fa75c015491153cfc93e7ea7a80112 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 19 Sep 2011 17:32:15 +0100 Subject: [PATCH] xen/pciback: use mutex rather than spinlock in passthrough backend To accommodate the call to the callback function from __xen_pcibk_publish_pci_roots(), which so far dropped and the re- acquired the lock without checking that the list didn't actually change, convert the code to use a mutex instead (observing that the code taking the lock won't ever get called from non-sleepable context). As a result, drop the bogus use of list_for_each_entry_safe() and remove the inappropriate dropping of the lock. Signed-off-by: Jan Beulich Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/xen-pciback/passthrough.c | 32 +++++++++++---------------- 1 file changed, 13 insertions(+), 19 deletions(-) diff --git a/drivers/xen/xen-pciback/passthrough.c b/drivers/xen/xen-pciback/passthrough.c index 1d32a9a42c01..e01e4b6ef267 100644 --- a/drivers/xen/xen-pciback/passthrough.c +++ b/drivers/xen/xen-pciback/passthrough.c @@ -7,13 +7,13 @@ #include #include -#include +#include #include "pciback.h" struct passthrough_dev_data { /* Access to dev_list must be protected by lock */ struct list_head dev_list; - spinlock_t lock; + struct mutex lock; }; static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev, @@ -24,9 +24,8 @@ static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev, struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry; struct pci_dev *dev = NULL; - unsigned long flags; - spin_lock_irqsave(&dev_data->lock, flags); + mutex_lock(&dev_data->lock); list_for_each_entry(dev_entry, &dev_data->dev_list, list) { if (domain == (unsigned int)pci_domain_nr(dev_entry->dev->bus) @@ -37,7 +36,7 @@ static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev, } } - spin_unlock_irqrestore(&dev_data->lock, flags); + mutex_unlock(&dev_data->lock); return dev; } @@ -48,7 +47,6 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev, { struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry; - unsigned long flags; unsigned int domain, bus, devfn; int err; @@ -57,9 +55,9 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev, return -ENOMEM; dev_entry->dev = dev; - spin_lock_irqsave(&dev_data->lock, flags); + mutex_lock(&dev_data->lock); list_add_tail(&dev_entry->list, &dev_data->dev_list); - spin_unlock_irqrestore(&dev_data->lock, flags); + mutex_unlock(&dev_data->lock); /* Publish this device. */ domain = (unsigned int)pci_domain_nr(dev->bus); @@ -76,9 +74,8 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev, struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry, *t; struct pci_dev *found_dev = NULL; - unsigned long flags; - spin_lock_irqsave(&dev_data->lock, flags); + mutex_lock(&dev_data->lock); list_for_each_entry_safe(dev_entry, t, &dev_data->dev_list, list) { if (dev_entry->dev == dev) { @@ -88,7 +85,7 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev, } } - spin_unlock_irqrestore(&dev_data->lock, flags); + mutex_unlock(&dev_data->lock); if (found_dev) pcistub_put_pci_dev(found_dev); @@ -102,7 +99,7 @@ static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev) if (!dev_data) return -ENOMEM; - spin_lock_init(&dev_data->lock); + mutex_init(&dev_data->lock); INIT_LIST_HEAD(&dev_data->dev_list); @@ -116,14 +113,14 @@ static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev, { int err = 0; struct passthrough_dev_data *dev_data = pdev->pci_dev_data; - struct pci_dev_entry *dev_entry, *e, *tmp; + struct pci_dev_entry *dev_entry, *e; struct pci_dev *dev; int found; unsigned int domain, bus; - spin_lock(&dev_data->lock); + mutex_lock(&dev_data->lock); - list_for_each_entry_safe(dev_entry, tmp, &dev_data->dev_list, list) { + list_for_each_entry(dev_entry, &dev_data->dev_list, list) { /* Only publish this device as a root if none of its * parent bridges are exported */ @@ -142,16 +139,13 @@ static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev, bus = (unsigned int)dev_entry->dev->bus->number; if (!found) { - spin_unlock(&dev_data->lock); err = publish_root_cb(pdev, domain, bus); if (err) break; - spin_lock(&dev_data->lock); } } - if (!err) - spin_unlock(&dev_data->lock); + mutex_unlock(&dev_data->lock); return err; } -- 2.39.5