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Message-ID: <3583141.yG8QGivRYt@vostro.rjw.lan>
Date: Mon, 21 Jan 2013 00:54:54 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Jiang Liu <liuj97@...il.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Jiang Liu <jiang.liu@...wei.com>,
Yinghai Lu <yinghai@...nel.org>,
Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
Yijing Wang <wangyijing@...wei.com>,
linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Toshi Kani <toshi.kani@...com>,
Myron Stowe <myron.stowe@...hat.com>
Subject: Re: [RFC PATCH v5 3/8] PCI: add a blocking notifier chain for PCI bus addition/removal
On Saturday, January 19, 2013 12:07:41 AM Jiang Liu wrote:
> When adding/removing a PCI bus, some other components want to be
> notified so they could update their states. For example, the pci_slot
> driver needs to create/destroy PCI slots attaching to the PCI bus.
> So introduce a dedicate blocking notifier chain for PCI bus
> addition/removal events. It could be extended to support PCI device
> addition/removal events in the future when needed.
>
> Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
> ---
> drivers/pci/bus.c | 24 ++++++++++++++++++++++++
> drivers/pci/pci.h | 1 +
> drivers/pci/probe.c | 2 ++
> drivers/pci/remove.c | 1 +
> include/linux/pci.h | 12 ++++++++++++
> 5 files changed, 40 insertions(+)
>
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 4c843cd..8bbd3f2 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -13,11 +13,33 @@
> #include <linux/errno.h>
> #include <linux/ioport.h>
> #include <linux/proc_fs.h>
> +#include <linux/notifier.h>
> #include <linux/init.h>
> #include <linux/slab.h>
>
> #include "pci.h"
>
> +static BLOCKING_NOTIFIER_HEAD(pci_bus_notifier_chain);
> +
> +int pci_bus_register_notifier(struct notifier_block *nb)
> +{
> + return blocking_notifier_chain_register(&pci_bus_notifier_chain, nb);
> +}
> +
> +int pci_bus_unregister_notifier(struct notifier_block *nb)
> +{
> + return blocking_notifier_chain_unregister(&pci_bus_notifier_chain, nb);
> +}
> +
> +void pci_bus_call_notifier(struct pci_bus *bus, unsigned long code)
> +{
> + int ret;
> +
> + ret = blocking_notifier_call_chain(&pci_bus_notifier_chain,
> + code, bus);
> + WARN_ON(ret != NOTIFY_DONE && ret != NOTIFY_OK);
I'm not sure if this is a good idea. WARN_ON() is quite a heavy tool.
> +}
> +
> void pci_add_resource_offset(struct list_head *resources, struct resource *res,
> resource_size_t offset)
> {
> @@ -197,6 +219,8 @@ int pci_bus_add_child(struct pci_bus *bus)
> if (retval)
> return retval;
>
> + pci_bus_call_notifier(bus, PCI_NOTIFY_POST_BUS_ADD);
> +
> bus->is_added = 1;
>
> /* Create legacy_io and legacy_mem files for this bus */
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 7414094..988e4b4 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -208,6 +208,7 @@ extern int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
> extern int pci_resource_bar(struct pci_dev *dev, int resno,
> enum pci_bar_type *type);
> extern int pci_bus_add_child(struct pci_bus *bus);
> +extern void pci_bus_call_notifier(struct pci_bus *bus, unsigned long code);
> extern void pci_enable_ari(struct pci_dev *dev);
> /**
> * pci_ari_enabled - query ARI forwarding status
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index adb77c6..7db6528 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1679,6 +1679,8 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> if (error)
> goto class_dev_reg_err;
>
> + pci_bus_call_notifier(b, PCI_NOTIFY_POST_BUS_ADD);
> +
> /* Create legacy_io and legacy_mem files for this bus */
> pci_create_legacy_files(b);
>
> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
> index 0d03026..2d8fbc8 100644
> --- a/drivers/pci/remove.c
> +++ b/drivers/pci/remove.c
> @@ -50,6 +50,7 @@ void pci_remove_bus(struct pci_bus *bus)
> up_write(&pci_bus_sem);
> if (bus->is_added) {
> pci_remove_legacy_files(bus);
> + pci_bus_call_notifier(bus, PCI_NOTIFY_PRE_BUS_DEL);
> device_del(&bus->dev);
> }
> put_device(&bus->dev);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index ee21795..12e5447 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1033,6 +1033,18 @@ const struct pci_device_id *pci_match_id(const struct pci_device_id *ids,
> int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
> int pass);
>
> +/*
> + * All notifiers below get called with the target struct pci_bus *bus as
> + * an argument.
> + * Note: all PCI bus notifier must return success. Currently there's no
> + * error handling if any notifier returns error code.
> + */
> +#define PCI_NOTIFY_POST_BUS_ADD 0x00000001 /* PCI bus has been added */
> +#define PCI_NOTIFY_PRE_BUS_DEL 0x00000002 /* PCI bus will be deleted */
I would call them PCI_EVENT_BUS_ADDED and PCI_EVENT_BUS_REMOVE, respectively.
> +
> +int pci_bus_register_notifier(struct notifier_block *nb);
> +int pci_bus_unregister_notifier(struct notifier_block *nb);
> +
> void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
> void *userdata);
> int pci_cfg_space_size_ext(struct pci_dev *dev);
Apart from the nitpicks above, looks good.
Thanks,
Rafael
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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