[Qemu-devel] [PATCH v2] pci: cleanly backout of pci_qdev_init()

[Qemu-devel] [PATCH v2] pci: cleanly backout of pci_qdev_init()

[Alex Williamson]

If the init function of a device fails, as might happen with device
assignment, we never undo the work done by do_pci_register_device().
This not only causes a bit of a memory leak, but also leaves a bogus
pointer in the bus devices array that can cause a segfault or
garbage data from 'info pci'.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

v2: Remove extraneous return from do_pci_unregister_device()(

 hw/pci.c |   16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/hw/pci.c b/hw/pci.c
index f167436..3ca5f09 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -625,6 +625,13 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
     return pci_dev;
 }
 
+static void do_pci_unregister_device(PCIDevice *pci_dev)
+{
+    qemu_free_irqs(pci_dev->irq);
+    pci_dev->bus->devices[pci_dev->devfn] = NULL;
+    pci_config_free(pci_dev);
+}
+
 PCIDevice *pci_register_device(PCIBus *bus, const char *name,
                                int instance_size, int devfn,
                                PCIConfigReadFunc *config_read,
@@ -680,10 +687,7 @@ static int pci_unregister_device(DeviceState *dev)
         return ret;
 
     pci_unregister_io_regions(pci_dev);
-
-    qemu_free_irqs(pci_dev->irq);
-    pci_dev->bus->devices[pci_dev->devfn] = NULL;
-    pci_config_free(pci_dev);
+    do_pci_unregister_device(pci_dev);
     return 0;
 }
 
@@ -1652,8 +1656,10 @@ static int pci_qdev_init(DeviceState *qdev, DeviceInfo *base)
     if (pci_dev == NULL)
         return -1;
     rc = info->init(pci_dev);
-    if (rc != 0)
+    if (rc != 0) {
+        do_pci_unregister_device(pci_dev);
         return rc;
+    }
 
     /* rom loading */
     if (pci_dev->romfile == NULL && info->romfile != NULL)

[Qemu-devel] Re: [PATCH v2] pci: cleanly backout of pci_qdev_init()

[Michael S. Tsirkin]

On Tue, May 11, 2010 at 06:44:21AM -0400, Alex Williamson wrote:
> If the init function of a device fails, as might happen with device
> assignment, we never undo the work done by do_pci_register_device().
> This not only causes a bit of a memory leak, but also leaves a bogus
> pointer in the bus devices array that can cause a segfault or
> garbage data from 'info pci'.
> 
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Thanks, applied.

> ---
> 
> v2: Remove extraneous return from do_pci_unregister_device()(
> 
>  hw/pci.c |   16 +++++++++++-----
>  1 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index f167436..3ca5f09 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -625,6 +625,13 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
>      return pci_dev;
>  }
>  
> +static void do_pci_unregister_device(PCIDevice *pci_dev)
> +{
> +    qemu_free_irqs(pci_dev->irq);
> +    pci_dev->bus->devices[pci_dev->devfn] = NULL;
> +    pci_config_free(pci_dev);
> +}
> +
>  PCIDevice *pci_register_device(PCIBus *bus, const char *name,
>                                 int instance_size, int devfn,
>                                 PCIConfigReadFunc *config_read,
> @@ -680,10 +687,7 @@ static int pci_unregister_device(DeviceState *dev)
>          return ret;
>  
>      pci_unregister_io_regions(pci_dev);
> -
> -    qemu_free_irqs(pci_dev->irq);
> -    pci_dev->bus->devices[pci_dev->devfn] = NULL;
> -    pci_config_free(pci_dev);
> +    do_pci_unregister_device(pci_dev);
>      return 0;
>  }
>  
> @@ -1652,8 +1656,10 @@ static int pci_qdev_init(DeviceState *qdev, DeviceInfo *base)
>      if (pci_dev == NULL)
>          return -1;
>      rc = info->init(pci_dev);
> -    if (rc != 0)
> +    if (rc != 0) {
> +        do_pci_unregister_device(pci_dev);
>          return rc;
> +    }
>  
>      /* rom loading */
>      if (pci_dev->romfile == NULL && info->romfile != NULL)
> 
> --
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