Re: [RFC PATCH v1 19/22] PCI/x86: enable PCI bus lock mechanism for x86 platforms

From: Bjorn Helgaas <bhelgaas@google.com>
To: Jiang Liu <liuj97@gmail.com>
Cc: Don Dutile <ddutile@redhat.com>, Yinghai Lu <yinghai@kernel.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
	Jiang Liu <jiang.liu@huawei.com>,
	Taku Izumi <izumi.taku@jp.fujitsu.com>,
	"Rafael J . Wysocki" <rjw@sisk.pl>,
	Yijing Wang <wangyijing@huawei.com>,
	Xinwei Hu <huxinwei@huawei.com>,
	linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [RFC PATCH v1 19/22] PCI/x86: enable PCI bus lock mechanism for x86 platforms
Date: Tue, 11 Sep 2012 17:22:30 -0600	[thread overview]
Message-ID: <CAErSpo7CYY0AucKj1_e=a8FDP6beQ6LKKaAEFbKxJp_ViwGhsA@mail.gmail.com> (raw)
In-Reply-To: <1344355862-2726-20-git-send-email-jiang.liu@huawei.com>

On Tue, Aug 7, 2012 at 10:10 AM, Jiang Liu <liuj97@gmail.com> wrote:
> This patch turns on PCI bus lock mechanism for x86 platforms. It also
> enhances x86 specific PCI implementation to support PCI bus lock.
>
> Signed-off-by: Jiang Liu <liuj97@gmail.com>
> ---
>  arch/x86/pci/acpi.c   |    6 +++++-
>  arch/x86/pci/common.c |   12 ++++++++++++
>  drivers/pci/Kconfig   |    3 +--
>  3 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index 2bb885a..c68dbdf 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -414,7 +414,8 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
>          * Maybe the desired pci bus has been already scanned. In such case
>          * it is unnecessary to scan the pci bus with the given domain,busnum.
>          */
> -       bus = pci_find_bus(domain, busnum);
> +       bus = __pci_get_and_lock_bus(domain, busnum,
> +                                    PCI_BUS_STATE_STOPPING - 1);
>         if (bus) {
>                 /*
>                  * If the desired bus exits, the content of bus->sysdata will
> @@ -449,6 +450,7 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
>                         pci_free_resource_list(&resources);
>                         __release_pci_root_info(info);
>                 }
> +               pci_bus_get(bus);
>         }
>
>         /* After the PCI-E bus has been walked and all devices discovered,
> @@ -475,6 +477,8 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
>  #endif
>         }
>
> +       pci_unlock_and_put_bus(bus);
> +
>         return bus;
>  }
>
> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
> index 0ad990a..8b7ae63 100644
> --- a/arch/x86/pci/common.c
> +++ b/arch/x86/pci/common.c
> @@ -667,6 +667,18 @@ struct pci_bus * __devinit pci_scan_bus_with_sysdata(int busno)
>         return pci_scan_bus_on_node(busno, &pci_root_ops, -1);
>  }
>
> +static DEFINE_MUTEX(pci_root_bus_mutex);
> +
> +void arch_pci_lock_host_bridge_hotplug(void)
> +{
> +       mutex_lock(&pci_root_bus_mutex);
> +}
> +
> +void arch_pci_unlock_host_bridge_hotplug(void)
> +{
> +       mutex_unlock(&pci_root_bus_mutex);
> +}

Are these left over from previous work?  I don't see any reference to
them elsewhere in your patch series.

>  /*
>   * NUMA info for PCI busses
>   *
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index a6df8b1..1bbe924 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -122,5 +122,4 @@ config PCI_LABEL
>         select NLS
>
>  config PCI_BUS_LOCK
> -       bool
> -       default n
> +       def_bool y if X86
> --
> 1.7.9.5
>