linux-kernel - Re: [RFC PATCH v2, part3 11/11] PCI, ACPI, pci_root: use PCI bus lock to protect PCI device hotplug

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Date:	Thu, 16 May 2013 21:59:27 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Jiang Liu <liuj97@...il.com>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Jiang Liu <jiang.liu@...wei.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Gu Zheng <guz.fnst@...fujitsu.com>,
	Toshi Kani <toshi.kani@...com>,
	Myron Stowe <myron.stowe@...hat.com>,
	Yijing Wang <wangyijing@...wei.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Len Brown <lenb@...nel.org>, Feng Tang <feng.tang@...el.com>,
	linux-acpi@...r.kernel.org
Subject: Re: [RFC PATCH v2, part3 11/11] PCI, ACPI, pci_root: use PCI bus lock to protect PCI device hotplug

On Thursday, May 16, 2013 11:50:59 PM Jiang Liu wrote:
> Use PCI bus lock to protect concurrent PCI device hotplug operations.
> 
> Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: x86@...nel.org
> Cc: Len Brown <lenb@...nel.org>
> Cc: "Rafael J. Wysocki" <rjw@...k.pl>
> Cc: Yinghai Lu <yinghai@...nel.org>
> Cc: Feng Tang <feng.tang@...el.com>
> Cc: linux-kernel@...r.kernel.org
> Cc: linux-acpi@...r.kernel.org

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  arch/ia64/pci/pci.c     |  2 +-
>  arch/x86/pci/acpi.c     |  3 ++-
>  drivers/acpi/pci_root.c | 14 ++++++++------
>  drivers/pci/Kconfig     |  2 +-
>  4 files changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
> index de1474f..6e91e87 100644
> --- a/arch/ia64/pci/pci.c
> +++ b/arch/ia64/pci/pci.c
> @@ -384,7 +384,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  	}
>  
>  	pci_scan_child_bus(pbus);
> -	return pbus;
> +	return pci_bus_get(pbus);
>  
>  out3:
>  	kfree(controller->window);
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index b972f04..6dddc06 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -534,7 +534,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  		 */
>  		memcpy(bus->sysdata, sd, sizeof(*sd));
>  		kfree(info);
> -		pci_bus_put(bus);
> +		BUG_ON(pci_bus_lock(bus, PCI_BUS_STATE_REMOVED - 1, true) < 0);
>  	} else {
>  		probe_pci_root_info(info, device, busnum, domain);
>  
> @@ -561,6 +561,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  			pci_set_host_bridge_release(
>  				to_pci_host_bridge(bus->bridge),
>  				release_pci_root_info, info);
> +			pci_bus_get(bus);
>  		} else {
>  			pci_free_resource_list(&resources);
>  			__release_pci_root_info(info);
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 21dda5a..eb01cc7 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -535,6 +535,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	}
>  
>  	pci_bus_add_devices(root->bus);
> +	pci_bus_unlock(root->bus, true);
>  	return 1;
>  
>  end:
> @@ -546,13 +547,14 @@ static void acpi_pci_root_remove(struct acpi_device *device)
>  {
>  	struct acpi_pci_root *root = acpi_driver_data(device);
>  
> -	pci_stop_root_bus(root->bus);
> -
> -	device_set_run_wake(root->bus->bridge, false);
> -	pci_acpi_remove_bus_pm_notifier(device);
> -
> -	pci_remove_root_bus(root->bus);
> +	if (pci_bus_lock(root->bus, PCI_BUS_STATE_REMOVED - 1, true) == 0) {
> +		pci_stop_root_bus(root->bus);
> +		device_set_run_wake(root->bus->bridge, false);
> +		pci_acpi_remove_bus_pm_notifier(device);
> +		pci_remove_root_bus(root->bus);
> +	}
>  
> +	pci_bus_put(root->bus);
>  	kfree(root);
>  }
>  
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index 92e69bd..5ae3504 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -121,4 +121,4 @@ config PCI_LABEL
>  	select NLS
>  
>  config PCI_BUS_LOCK
> -	def_bool n
> +	def_bool y if (X86 || IA64)
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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