ping..
在 2016/6/23 19:42, Yijing Wang 写道:
> pci_host_bridge holds the top resources(IO port/Mem/bus),
> now we release pci_host_bridge resources in
> acpi_pci_root_release_info() which would be called when
> pci_host_bridge device refcount reach 0. In some cases,
> pci_host_bridge refcount cannot reach 0 after we remove
> pci root bus in pci_remove_root_bus(). Then if we want to
> hot add pci root bus, we cannot use pci_host_bridge
> resources because of conflicts with old resources which are
> still in system. I think this is not reasonable.
>
> 1. For pci devices, we would release their resources in
> pci_destroy_dev() regardless of pci device refcount.
> 2. When we try to remove pci root bus, there is no devices
> need to use the pci_host_bridge resources again, release
> pci_host_bridge resources is safe.
> 3. In some cases, users woule make mistake, for example,
> user get a pci device(increase refcount), but forget to
> put this device, then if we do hotplug pci root bus,
> it would make all pci devices cannot work after hot add.
>
> I found this issue in the following case:
> 1. I have a raid pci device in my system;
> 2. I mount a disk which connect to this raid.
> 3. hot remove the pci root bus.
> 4. hot add the pci root bus.
> 5. found the resource conflicts for the children pci devices under this root bus.
>
> pci_root_bus increase a refcount at pci_host_bridge.
> pci_root_bus decrease a refcount at pci_host_bridge in
> release_pcibus_dev() when pci_root_bus device refcount reach 0.
>
> pci_dev increase a refcount at pci_bus in pci_alloc_dev().
> pci_dev decrease a refcount at pci_bus in pci_release_dev()
> when pci_dev refcount reach 0.
>
> If any pci device refcount cannot reach 0, then its pci_bus
> refcount cannot reach 0 too, the result is pci_host_bridge
> refcount cannot reach 0.
>
> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
> ---
> drivers/acpi/pci_root.c | 11 -----------
> drivers/pci/host-bridge.c | 15 +++++++++++++++
> drivers/pci/pci.h | 2 +-
> drivers/pci/remove.c | 1 +
> 4 files changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index d144168..c5142d0 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -839,17 +839,6 @@ static void __acpi_pci_root_release_info(struct acpi_pci_root_info *info)
>
> static void acpi_pci_root_release_info(struct pci_host_bridge *bridge)
> {
> - struct resource *res;
> - struct resource_entry *entry;
> -
> - resource_list_for_each_entry(entry, &bridge->windows) {
> - res = entry->res;
> - if (res->flags & IORESOURCE_IO)
> - pci_unmap_iospace(res);
> - if (res->parent &&
> - (res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
> - release_resource(res);
> - }
> __acpi_pci_root_release_info(bridge->release_data);
> }
>
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index 5f4a2e0..3594967 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -8,6 +8,21 @@
>
> #include "pci.h"
>
> +void release_host_bridge_resources(struct pci_host_bridge *bridge)
> +{
> + struct resource *res;
> + struct resource_entry *entry;
> +
> + resource_list_for_each_entry(entry, &bridge->windows) {
> + res = entry->res;
> + if (res->flags & IORESOURCE_IO)
> + pci_unmap_iospace(res);
> + if (res->parent &&
> + (res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
> + release_resource(res);
> + }
> +}
> +
> static struct pci_bus *find_pci_root_bus(struct pci_bus *bus)
> {
> while (bus->parent)
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 9730c47..46725d9 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -11,7 +11,7 @@ extern const unsigned char pcie_link_speed[];
> bool pcie_cap_has_lnkctl(const struct pci_dev *dev);
>
> /* Functions internal to the PCI core code */
> -
> +void release_host_bridge_resources(struct pci_host_bridge *bridge);
> int pci_create_sysfs_dev_files(struct pci_dev *pdev);
> void pci_remove_sysfs_dev_files(struct pci_dev *pdev);
> #if !defined(CONFIG_DMI) && !defined(CONFIG_ACPI)
> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
> index d1ef7ac..a42b396 100644
> --- a/drivers/pci/remove.c
> +++ b/drivers/pci/remove.c
> @@ -161,6 +161,7 @@ void pci_remove_root_bus(struct pci_bus *bus)
> pci_remove_bus(bus);
> host_bridge->bus = NULL;
>
> + release_host_bridge_resources(host_bridge);
> /* remove the host bridge */
> device_unregister(&host_bridge->dev);
> }
>
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