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Date: Tue, 6 Mar 2012 21:31:24 -0700
From: Bjorn Helgaas <bjorn.helgaas@...il.com>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Jesse Barnes <jbarnes@...tuousgeek.org>, x86 <x86@...nel.org>,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
Randy Dunlap <rdunlap@...otime.net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-doc@...r.kernel.org
Subject: Re: [PATCH 19/23] PCI: add /sys/bus/pci/rescan_root
On Tue, Mar 6, 2012 at 12:13 AM, Yinghai Lu <yinghai@...nel.org> wrote:
>
> It will be used to rediscover removed pci root buses.
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: Randy Dunlap <rdunlap@...otime.net>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: linux-doc@...r.kernel.org
> ---
> Documentation/ABI/testing/sysfs-bus-pci | 9 +++++++++
> drivers/pci/pci-sysfs.c | 21 +++++++++++++++++++++
> 2 files changed, 30 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-pci
> b/Documentation/ABI/testing/sysfs-bus-pci
> index 22392de..eb826bd 100644
> --- a/Documentation/ABI/testing/sysfs-bus-pci
> +++ b/Documentation/ABI/testing/sysfs-bus-pci
> @@ -66,6 +66,15 @@ Description:
> re-discover previously removed devices.
> Depends on CONFIG_HOTPLUG.
>
> +What: /sys/bus/pci/rescan_root
> +Date: March 2012
> +Contact: Linux PCI developers <linux-pci@...r.kernel.org>
> +Description:
> + Writing a non-zero value to this attribute will
> + cause a rescan of all PCI root buses in the system, and
> + re-discover previously removed PCI root buses.
This seems sort of backwards to me. Architecture-specific code
enumerated the host bridges/root buses in the first place, not the PCI
core. Now we're asking the PCI core (/sys/bus/pci) to re-enumerate
them.
But maybe it's still the right answer, I dunno.
> + Depends on CONFIG_HOTPLUG.
> +
> What: /sys/bus/pci/devices/.../msi_irqs/
> Date: September, 2011
> Contact: Neil Horman <nhorman@...driver.com>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index f855b4b..d6221e5 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -302,8 +302,29 @@ static ssize_t bus_rescan_store(struct bus_type *bus,
> const char *buf,
> return count;
> }
>
> +void __weak acpi_pci_root_rescan(void) { }
> +void __weak pcibios_root_rescan(void) { }
> +
> +static ssize_t bus_rescan_root_store(struct bus_type *bus, const char
> *buf,
> + size_t count)
> +{
> + unsigned long val;
> +
> + if (strict_strtoul(buf, 0, &val) < 0)
> + return -EINVAL;
> +
> + if (val) {
> + mutex_lock(&pci_remove_rescan_mutex);
> + acpi_pci_root_rescan();
This architecture-dependent function name should not be here. How
will we make this work for powerpc, sparc, etc.?
> + pcibios_root_rescan();
> + mutex_unlock(&pci_remove_rescan_mutex);
> + }
> + return count;
> +}
> +
> struct bus_attribute pci_bus_attrs[] = {
> __ATTR(rescan, (S_IWUSR|S_IWGRP), NULL, bus_rescan_store),
> + __ATTR(rescan_root, (S_IWUSR|S_IWGRP), NULL,
> bus_rescan_root_store),
> __ATTR_NULL
> };
>
> --
> 1.7.7
>
> --
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