PCI: Simplify IOV implementation and fix reference count races

Trivial changes to IOV:

  1) use new PCI interfaces to simplify IOV implementation
  2) fix some reference count related race windows

[bhelgaas: fix virtfn_add() add bus/alloc dev error paths]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ram Pai <linuxram@us.ibm.com>

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 8f1e1174b71fd29fca2c412445f461c8a80796a2..5fffca995a9143313bbe352127083f26145e1389 100644 (file)
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -51,24 +51,16 @@ static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
        return child;
 }
 
-static void virtfn_remove_bus(struct pci_bus *bus, int busnr)
+static void virtfn_remove_bus(struct pci_bus *physbus, struct pci_bus *virtbus)
 {
-       struct pci_bus *child;
-
-       if (bus->number == busnr)
-               return;
-
-       child = pci_find_bus(pci_domain_nr(bus), busnr);
-       BUG_ON(!child);
-
-       if (list_empty(&child->devices))
-               pci_remove_bus(child);
+       if (physbus != virtbus && list_empty(&virtbus->devices))
+               pci_remove_bus(virtbus);
 }
 
 static int virtfn_add(struct pci_dev *dev, int id, int reset)
 {
        int i;
-       int rc;
+       int rc = -ENOMEM;
        u64 size;
        char buf[VIRTFN_ID_LEN];
        struct pci_dev *virtfn;
@@ -76,18 +68,15 @@ static int virtfn_add(struct pci_dev *dev, int id, int reset)
        struct pci_sriov *iov = dev->sriov;
        struct pci_bus *bus;
 
-       virtfn = pci_alloc_dev(NULL);
-       if (!virtfn)
-               return -ENOMEM;
-
        mutex_lock(&iov->dev->sriov->lock);
        bus = virtfn_add_bus(dev->bus, virtfn_bus(dev, id));
-       if (!bus) {
-               kfree(virtfn);
-               mutex_unlock(&iov->dev->sriov->lock);
-               return -ENOMEM;
-       }
-       virtfn->bus = pci_bus_get(bus);
+       if (!bus)
+               goto failed;
+
+       virtfn = pci_alloc_dev(bus);
+       if (!virtfn)
+               goto failed0;
+
        virtfn->devfn = virtfn_devfn(dev, id);
        virtfn->vendor = dev->vendor;
        pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_DID, &virtfn->device);
@@ -136,7 +125,9 @@ failed1:
        pci_dev_put(dev);
        mutex_lock(&iov->dev->sriov->lock);
        pci_stop_and_remove_bus_device(virtfn);
-       virtfn_remove_bus(dev->bus, virtfn_bus(dev, id));
+failed0:
+       virtfn_remove_bus(dev->bus, bus);
+failed:
        mutex_unlock(&iov->dev->sriov->lock);
 
        return rc;
@@ -145,20 +136,15 @@ failed1:
 static void virtfn_remove(struct pci_dev *dev, int id, int reset)
 {
        char buf[VIRTFN_ID_LEN];
-       struct pci_bus *bus;
        struct pci_dev *virtfn;
        struct pci_sriov *iov = dev->sriov;
 
-       bus = pci_find_bus(pci_domain_nr(dev->bus), virtfn_bus(dev, id));
-       if (!bus)
-               return;
-
-       virtfn = pci_get_slot(bus, virtfn_devfn(dev, id));
+       virtfn = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus),
+                                            virtfn_bus(dev, id),
+                                            virtfn_devfn(dev, id));
        if (!virtfn)
                return;
 
-       pci_dev_put(virtfn);
-
        if (reset) {
                device_release_driver(&virtfn->dev);
                __pci_reset_function(virtfn);
@@ -176,9 +162,11 @@ static void virtfn_remove(struct pci_dev *dev, int id, int reset)
 
        mutex_lock(&iov->dev->sriov->lock);
        pci_stop_and_remove_bus_device(virtfn);
-       virtfn_remove_bus(dev->bus, virtfn_bus(dev, id));
+       virtfn_remove_bus(dev->bus, virtfn->bus);
        mutex_unlock(&iov->dev->sriov->lock);
 
+       /* balance pci_get_domain_bus_and_slot() */
+       pci_dev_put(virtfn);
        pci_dev_put(dev);
 }
 
@@ -335,13 +323,14 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
                if (!pdev)
                        return -ENODEV;
 
-               pci_dev_put(pdev);
-
-               if (!pdev->is_physfn)
+               if (!pdev->is_physfn) {
+                       pci_dev_put(pdev);
                        return -ENODEV;
+               }
 
                rc = sysfs_create_link(&dev->dev.kobj,
                                        &pdev->dev.kobj, "dep_link");
+               pci_dev_put(pdev);
                if (rc)
                        return rc;
        }