[Xen-devel] [PATCH 2/3] linux-2.6.18/pciback: properly clean up after calling pcistub_device_find()

["Jan Beulich" <JBeulich@xxxxxxxx>]

As the function calls pcistub_device_get() before returning non-NULL,
its callers need to take care of calling pcistub_device_put() on
(mostly, but not exclusively) error paths.

Otoh, the function already guarantees that the 'dev' member is non-NULL
upon successful return, so callers do not need to check for this a
second time.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/drivers/xen/pciback/pci_stub.c
+++ b/drivers/xen/pciback/pci_stub.c
@@ -642,14 +642,14 @@ static pci_ers_result_t pciback_slot_res
                dev_err(&dev->dev, "pciback device is not connected or owned"
                        " by HVM, kill it\n");
                kill_domain_by_device(psdev);
-               goto release;
+               goto end;
        }
 
        if ( !test_bit(_XEN_PCIB_AERHANDLER, 
                (unsigned long *)&psdev->pdev->sh_info->flags) ) {
                dev_err(&dev->dev, 
                        "guest with no AER driver should have been killed\n");
-               goto release;
+               goto end;
        }
        result = common_process(psdev, 1, XEN_PCI_OP_aer_slotreset, result);
 
@@ -659,9 +659,9 @@ static pci_ers_result_t pciback_slot_res
                        "No AER slot_reset service or disconnected!\n");
                kill_domain_by_device(psdev);
        }
-release:
-       pcistub_device_put(psdev);
 end:
+       if (psdev)
+               pcistub_device_put(psdev);
        up_write(&pcistub_sem);
        return result;
 
@@ -702,14 +702,14 @@ static pci_ers_result_t pciback_mmio_ena
                dev_err(&dev->dev, "pciback device is not connected or owned"
                        " by HVM, kill it\n");
                kill_domain_by_device(psdev);
-               goto release;
+               goto end;
        }
 
        if ( !test_bit(_XEN_PCIB_AERHANDLER, 
                (unsigned long *)&psdev->pdev->sh_info->flags) ) {
                dev_err(&dev->dev, 
                        "guest with no AER driver should have been killed\n");
-               goto release;
+               goto end;
        }
        result = common_process(psdev, 1, XEN_PCI_OP_aer_mmio, result);
 
@@ -719,9 +719,9 @@ static pci_ers_result_t pciback_mmio_ena
                        "No AER mmio_enabled service or disconnected!\n");
                kill_domain_by_device(psdev);
        }
-release:
-       pcistub_device_put(psdev);
 end:
+       if (psdev)
+               pcistub_device_put(psdev);
        up_write(&pcistub_sem);
        return result;
 }
@@ -762,7 +762,7 @@ static pci_ers_result_t pciback_error_de
                dev_err(&dev->dev, "pciback device is not connected or owned"
                        " by HVM, kill it\n");
                kill_domain_by_device(psdev);
-               goto release;
+               goto end;
        }
 
        /*Guest owns the device yet no aer handler regiested, kill guest*/
@@ -770,7 +770,7 @@ static pci_ers_result_t pciback_error_de
                (unsigned long *)&psdev->pdev->sh_info->flags) ) {
                dev_dbg(&dev->dev, "guest may have no aer driver, kill it\n");
                kill_domain_by_device(psdev);
-               goto release;
+               goto end;
        }
        result = common_process(psdev, error, XEN_PCI_OP_aer_detected, result);
 
@@ -780,9 +780,9 @@ static pci_ers_result_t pciback_error_de
                        "No AER error_detected service or disconnected!\n");
                kill_domain_by_device(psdev);
        }
-release:
-       pcistub_device_put(psdev);
 end:
+       if (psdev)
+               pcistub_device_put(psdev);
        up_write(&pcistub_sem);
        return result;
 }
@@ -818,7 +818,7 @@ static void pciback_error_resume(struct 
                dev_err(&dev->dev, "pciback device is not connected or owned"
                        " by HVM, kill it\n");
                kill_domain_by_device(psdev);
-               goto release;
+               goto end;
        }
 
        if ( !test_bit(_XEN_PCIB_AERHANDLER, 
@@ -826,12 +826,12 @@ static void pciback_error_resume(struct 
                dev_err(&dev->dev, 
                        "guest with no AER driver should have been killed\n");
                kill_domain_by_device(psdev);
-               goto release;
+               goto end;
        }
        common_process(psdev, 1, XEN_PCI_OP_aer_resume, 
PCI_ERS_RESULT_RECOVERED);
-release:
-       pcistub_device_put(psdev);
 end:
+       if (psdev)
+               pcistub_device_put(psdev);
        up_write(&pcistub_sem);
        return;
 }
@@ -988,7 +988,7 @@ static int pcistub_reg_add(int domain, i
        struct config_field *field;
 
        psdev = pcistub_device_find(domain, bus, slot, func);
-       if (!psdev || !psdev->dev) {
+       if (!psdev) {
                err = -ENODEV;
                goto out;
        }
@@ -1012,6 +1012,8 @@ static int pcistub_reg_add(int domain, i
        if (err)
                kfree(field);
       out:
+       if (psdev)
+               pcistub_device_put(psdev);
        return err;
 }
 
@@ -1163,10 +1165,7 @@ static ssize_t permissive_add(struct dev
                err = -ENODEV;
                goto out;
        }
-       if (!psdev->dev) {
-               err = -ENODEV;
-               goto release;
-       }
+
        dev_data = pci_get_drvdata(psdev->dev);
        /* the driver data for a device should never be null at this point */
        if (!dev_data) {
@@ -1219,14 +1218,18 @@ DRIVER_ATTR(permissive, S_IRUSR | S_IWUS
 int pciback_get_owner(struct pci_dev *dev)
 {
        struct pcistub_device *psdev;
+       int rc;
 
        psdev = pcistub_device_find(pci_domain_nr(dev->bus), dev->bus->number,
                        PCI_SLOT(dev->devfn), PCI_FUNC(dev->devfn));
 
-       if (!psdev || !psdev->pdev)
-               return -1;
+       if (!psdev)
+               return -ESRCH;
+
+       rc = psdev->pdev ? psdev->pdev->xdev->otherend_id : -EINVAL;
 
-       return psdev->pdev->xdev->otherend_id;
+       pcistub_device_put(psdev);
+       return rc;
 }
 #endif

Attachment: xen-pciback-find-error-paths.patch
Description: Text document

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