Patchwork [v6,2/2] PCI: acpiphp: remove all functions in slot, even without ACPI _EJx

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Submitter Bjorn Helgaas
Date May 23, 2012, 4:35 a.m.
Message ID <20120523043511.13449.22006.stgit@bhelgaas.mtv.corp.google.com>
Download mbox | patch
Permalink /patch/160808/
State Superseded
Headers show

Comments

Bjorn Helgaas - May 23, 2012, 4:35 a.m.
From: Amos Kong <kongjianjun@gmail.com>

When we add a device with acpiphp, we enumerate all functions in the
slot with pci_scan_slot(), regardless of whether they have associated
ACPI methods such as _EJ0.

When removing the device, we previously removed only the functions
with those ACPI methods.  This patch makes the remove symmetric with the
add: we remove all functions in the slot, whether they have associated
ACPI methods or not.

With qemu-kvm and SeaBIOS, we can build a multi-function device where
only function 0 has _EJ0 and _ADR (see bugzilla below).  Removing and
re-adding that device works correctly with Windows guests.  This patch
makes it also work in Linux guests.

[bhelgaas: restructure loop iteration, pull out of slot->funcs loop]
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=43219
Signed-off-by: Amos Kong <kongjianjun@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/hotplug/acpiphp_glue.c |   39 +++++++++++++++++++++++++++---------
 1 files changed, 29 insertions(+), 10 deletions(-)


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Yinghai Lu - May 23, 2012, 5:04 a.m.
On Tue, May 22, 2012 at 9:35 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> From: Amos Kong <kongjianjun@gmail.com>
>
> When we add a device with acpiphp, we enumerate all functions in the
> slot with pci_scan_slot(), regardless of whether they have associated
> ACPI methods such as _EJ0.
>
> When removing the device, we previously removed only the functions
> with those ACPI methods.  This patch makes the remove symmetric with the
> add: we remove all functions in the slot, whether they have associated
> ACPI methods or not.
>
> With qemu-kvm and SeaBIOS, we can build a multi-function device where
> only function 0 has _EJ0 and _ADR (see bugzilla below).  Removing and
> re-adding that device works correctly with Windows guests.  This patch
> makes it also work in Linux guests.
>
> [bhelgaas: restructure loop iteration, pull out of slot->funcs loop]
> Reference: https://bugzilla.kernel.org/show_bug.cgi?id=43219
> Signed-off-by: Amos Kong <kongjianjun@gmail.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/pci/hotplug/acpiphp_glue.c |   39 +++++++++++++++++++++++++++---------
>  1 files changed, 29 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index c8f9991..9aff4f0 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -878,6 +878,21 @@ static void disable_bridges(struct pci_bus *bus)
>        }
>  }
>
> +/* return first device in slot, acquiring a reference on it */
> +static struct pci_dev *dev_in_slot(struct acpiphp_slot *slot)
> +{
> +       struct pci_bus *bus = slot->bridge->pci_bus;
> +       struct pci_dev *dev;
> +
> +       down_read(&pci_bus_sem);
> +       list_for_each_entry(dev, &bus->devices, bus_list)
> +               if (PCI_SLOT(dev->devfn) == slot->device)
> +                       return pci_dev_get(dev);
> +       up_read(&pci_bus_sem);

Do you need to keep that pci_bus_sem operation pair on return path?

> +
> +       return NULL;
> +}
> +
>  /**
>  * disable_device - disable a slot
>  * @slot: ACPI PHP slot
> @@ -902,18 +917,22 @@ static int disable_device(struct acpiphp_slot *slot)
>                                                (u32)1, NULL, NULL);
>                        func->bridge = NULL;
>                }
> +       }
>
> -               pdev = pci_get_slot(slot->bridge->pci_bus,
> -                                   PCI_DEVFN(slot->device, func->function));
> -               if (pdev) {
> -                       pci_stop_bus_device(pdev);
> -                       if (pdev->subordinate) {
> -                               disable_bridges(pdev->subordinate);
> -                               pci_disable_device(pdev);
> -                       }
> -                       __pci_remove_bus_device(pdev);
> -                       pci_dev_put(pdev);
> +       /*
> +        * enable_device() enumerates all functions in this device via
> +        * pci_scan_slot(), whether they have associated ACPI hotplug
> +        * methods (_EJ0, etc.) or not.  Therefore, we remove all functions
> +        * here.
> +        */
> +       while ((pdev = dev_in_slot(slot))) {
> +               pci_stop_bus_device(pdev);
> +               if (pdev->subordinate) {
> +                       disable_bridges(pdev->subordinate);
> +                       pci_disable_device(pdev);
>                }
> +               __pci_remove_bus_device(pdev);
> +               pci_dev_put(pdev);
>        }
>
>        list_for_each_entry(func, &slot->funcs, sibling) {
>
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Patch

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index c8f9991..9aff4f0 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -878,6 +878,21 @@  static void disable_bridges(struct pci_bus *bus)
 	}
 }
 
+/* return first device in slot, acquiring a reference on it */
+static struct pci_dev *dev_in_slot(struct acpiphp_slot *slot)
+{
+	struct pci_bus *bus = slot->bridge->pci_bus;
+	struct pci_dev *dev;
+
+	down_read(&pci_bus_sem);
+	list_for_each_entry(dev, &bus->devices, bus_list)
+		if (PCI_SLOT(dev->devfn) == slot->device)
+			return pci_dev_get(dev);
+	up_read(&pci_bus_sem);
+
+	return NULL;
+}
+
 /**
  * disable_device - disable a slot
  * @slot: ACPI PHP slot
@@ -902,18 +917,22 @@  static int disable_device(struct acpiphp_slot *slot)
 						(u32)1, NULL, NULL);
 			func->bridge = NULL;
 		}
+	}
 
-		pdev = pci_get_slot(slot->bridge->pci_bus,
-				    PCI_DEVFN(slot->device, func->function));
-		if (pdev) {
-			pci_stop_bus_device(pdev);
-			if (pdev->subordinate) {
-				disable_bridges(pdev->subordinate);
-				pci_disable_device(pdev);
-			}
-			__pci_remove_bus_device(pdev);
-			pci_dev_put(pdev);
+	/*
+	 * enable_device() enumerates all functions in this device via
+	 * pci_scan_slot(), whether they have associated ACPI hotplug
+	 * methods (_EJ0, etc.) or not.  Therefore, we remove all functions
+	 * here.
+	 */
+	while ((pdev = dev_in_slot(slot))) {
+		pci_stop_bus_device(pdev);
+		if (pdev->subordinate) {
+			disable_bridges(pdev->subordinate);
+			pci_disable_device(pdev);
 		}
+		__pci_remove_bus_device(pdev);
+		pci_dev_put(pdev);
 	}
 
 	list_for_each_entry(func, &slot->funcs, sibling) {