5 files changed, 33 insertions, 16 deletions

diff --git a/drivers/xen/xen-pciback/passthrough.c b/drivers/xen/xen-pciback/passthrough.c
index 828dddc360df..f16a30e2a110 100644
--- a/drivers/xen/xen-pciback/passthrough.c
+++ b/drivers/xen/xen-pciback/passthrough.c
@@ -69,7 +69,7 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
 }
 
 static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
-                                        struct pci_dev *dev)
+                                        struct pci_dev *dev, bool lock)
 {
         struct passthrough_dev_data *dev_data = pdev->pci_dev_data;
         struct pci_dev_entry *dev_entry, *t;
@@ -87,8 +87,13 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
 
         mutex_unlock(&dev_data->lock);
 
-        if (found_dev)
+        if (found_dev) {
+                if (lock)
+                        device_lock(&found_dev->dev);
                 pcistub_put_pci_dev(found_dev);
+                if (lock)
+                        device_unlock(&found_dev->dev);
+        }
 }
 
 static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
@@ -156,8 +161,11 @@ static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
         struct pci_dev_entry *dev_entry, *t;
 
         list_for_each_entry_safe(dev_entry, t, &dev_data->dev_list, list) {
+                struct pci_dev *dev = dev_entry->dev;
                 list_del(&dev_entry->list);
-                pcistub_put_pci_dev(dev_entry->dev);
+                device_lock(&dev->dev);
+                pcistub_put_pci_dev(dev);
+                device_unlock(&dev->dev);
                 kfree(dev_entry);
         }
 
diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 017069a455d4..9cbe1a31c1e5 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -250,6 +250,8 @@ struct pci_dev *pcistub_get_pci_dev(struct xen_pcibk_device *pdev,
  *  - 'echo BDF > unbind' with a guest still using it. See pcistub_remove
  *
  *  As such we have to be careful.
+ *
+ *  To make this easier, the caller has to hold the device lock.
  */
 void pcistub_put_pci_dev(struct pci_dev *dev)
 {
@@ -276,11 +278,8 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
         /* Cleanup our device
          * (so it's ready for the next domain)
          */
-
-        /* This is OK - we are running from workqueue context
-         * and want to inhibit the user from fiddling with 'reset'
-         */
-        pci_reset_function(dev);
+        lockdep_assert_held(&dev->dev.mutex);
+        __pci_reset_function_locked(dev);
         pci_restore_state(dev);
 
         /* This disables the device. */
@@ -567,7 +566,8 @@ static void pcistub_remove(struct pci_dev *dev)
                         /* N.B. This ends up calling pcistub_put_pci_dev which ends up
                          * doing the FLR. */
                         xen_pcibk_release_pci_dev(found_psdev->pdev,
-                                                found_psdev->dev);
+                                                found_psdev->dev,
+                                                false /* caller holds the lock. */);
                 }
 
                 spin_lock_irqsave(&pcistub_devices_lock, flags);
diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
index f72af87640e0..58e38d586f52 100644
--- a/drivers/xen/xen-pciback/pciback.h
+++ b/drivers/xen/xen-pciback/pciback.h
@@ -99,7 +99,8 @@ struct xen_pcibk_backend {
                     unsigned int *domain, unsigned int *bus,
                     unsigned int *devfn);
         int (*publish)(struct xen_pcibk_device *pdev, publish_pci_root_cb cb);
-        void (*release)(struct xen_pcibk_device *pdev, struct pci_dev *dev);
+        void (*release)(struct xen_pcibk_device *pdev, struct pci_dev *dev,
+                        bool lock);
         int (*add)(struct xen_pcibk_device *pdev, struct pci_dev *dev,
                    int devid, publish_pci_dev_cb publish_cb);
         struct pci_dev *(*get)(struct xen_pcibk_device *pdev,
@@ -122,10 +123,10 @@ static inline int xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
 }
 
 static inline void xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
-                                             struct pci_dev *dev)
+                                             struct pci_dev *dev, bool lock)
 {
         if (xen_pcibk_backend && xen_pcibk_backend->release)
-                return xen_pcibk_backend->release(pdev, dev);
+                return xen_pcibk_backend->release(pdev, dev, lock);
 }
 
 static inline struct pci_dev *
diff --git a/drivers/xen/xen-pciback/vpci.c b/drivers/xen/xen-pciback/vpci.c
index 51afff96c515..c99f8bb1c56c 100644
--- a/drivers/xen/xen-pciback/vpci.c
+++ b/drivers/xen/xen-pciback/vpci.c
@@ -145,7 +145,7 @@ out:
 }
 
 static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
-                                        struct pci_dev *dev)
+                                        struct pci_dev *dev, bool lock)
 {
         int slot;
         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
@@ -169,8 +169,13 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
 out:
         mutex_unlock(&vpci_dev->lock);
 
-        if (found_dev)
+        if (found_dev) {
+                if (lock)
+                        device_lock(&found_dev->dev);
                 pcistub_put_pci_dev(found_dev);
+                if (lock)
+                        device_unlock(&found_dev->dev);
+        }
 }
 
 static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
@@ -208,8 +213,11 @@ static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
                 struct pci_dev_entry *e, *tmp;
                 list_for_each_entry_safe(e, tmp, &vpci_dev->dev_list[slot],
                                          list) {
+                        struct pci_dev *dev = e->dev;
                         list_del(&e->list);
-                        pcistub_put_pci_dev(e->dev);
+                        device_lock(&dev->dev);
+                        pcistub_put_pci_dev(dev);
+                        device_unlock(&dev->dev);
                         kfree(e);
                 }
         }
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index ad8d30c088fe..eeee499d4b3c 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -291,7 +291,7 @@ static int xen_pcibk_remove_device(struct xen_pcibk_device *pdev,
 
         /* N.B. This ends up calling pcistub_put_pci_dev which ends up
          * doing the FLR. */
-        xen_pcibk_release_pci_dev(pdev, dev);
+        xen_pcibk_release_pci_dev(pdev, dev, true /* use the lock. */);
 
 out:
         return err;