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    Subject[PATCH v3 01/30] PCI: Rip out pci_bus_add_devices() from pci_scan_bus()
    Date
    Pci_bus_add_devices() should not be placed in pci_scan_bus().
    Now pci device will be added to driver core once its
    creation. All things left in pci_bus_add_devices() are
    driver attachment and other trivial sysfs things.
    Pci_scan_bus() should be the function responsible for
    scanning PCI devices, not including driver attachment.
    Other, some callers(m68k,unicore32,alpha) of pci_scan_bus()
    will call pci_bus_size_bridges() and pci_bus_assign_resources()
    after pci_scan_bus().

    E.g.
    In m68k
    mcf_pci_init()
    pci_scan_bus()
    ...
    pci_bus_add_devices() --- try to attach driver
    pci_fixup_irqs()
    pci_bus_size_bridges()
    pci_bus_assign_resources()

    Above code flow make pci scan logic obscure, resources should
    be assigned correctly before attaching driver. Because
    pci_scan_bus() mostly be called in system boot path, when
    before drivers are loaded(in module_init), so no pci scan
    issues will occur. Most pci_scan_bus() callers additionally
    call pci_bus_size_bridges() and pci_bus_assign_resources()
    after pci_scan_bus(), we could rip out pci_bus_add_devices()
    for better code readability. After applied this patch,
    pci_scan_bus() should be used like:

    pci_scan_bus() (mandatory)
    pci_fixup_irqs() (optional)
    pci_bus_size_bridges() (optional)
    pci_pci_bus_assign_resources() (optional)
    pci_bus_add_devices() (mandatory)

    Signed-off-by: Yijing Wang <wangyijing@huawei.com>
    CC: "David S. Miller" <davem@davemloft.net>
    CC: Geert Uytterhoeven <geert@linux-m68k.org>
    CC: Guan Xuetao <gxt@mprc.pku.edu.cn>
    CC: Richard Henderson <rth@twiddle.net>
    CC: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
    CC: Matt Turner <mattst88@gmail.com>
    CC: linux-alpha@vger.kernel.org
    CC: linux-m68k@lists.linux-m68k.org
    CC: sparclinux@vger.kernel.org
    ---
    arch/alpha/kernel/sys_nautilus.c | 1 +
    arch/m68k/coldfire/pci.c | 1 +
    arch/sparc/kernel/pcic.c | 2 ++
    arch/unicore32/kernel/pci.c | 11 +++--------
    drivers/pci/hotplug/ibmphp_core.c | 6 ++++--
    drivers/pci/probe.c | 1 -
    6 files changed, 11 insertions(+), 11 deletions(-)

    diff --git a/arch/alpha/kernel/sys_nautilus.c b/arch/alpha/kernel/sys_nautilus.c
    index 837c0fa..4ae4a40 100644
    --- a/arch/alpha/kernel/sys_nautilus.c
    +++ b/arch/alpha/kernel/sys_nautilus.c
    @@ -253,6 +253,7 @@ nautilus_init_pci(void)
    for the root bus, so just clear it. */
    bus->self = NULL;
    pci_fixup_irqs(alpha_mv.pci_swizzle, alpha_mv.pci_map_irq);
    + pci_bus_add_devices(bus);
    }

    /*
    diff --git a/arch/m68k/coldfire/pci.c b/arch/m68k/coldfire/pci.c
    index df96792..d45f087 100644
    --- a/arch/m68k/coldfire/pci.c
    +++ b/arch/m68k/coldfire/pci.c
    @@ -319,6 +319,7 @@ static int __init mcf_pci_init(void)
    pci_fixup_irqs(pci_common_swizzle, mcf_pci_map_irq);
    pci_bus_size_bridges(rootbus);
    pci_bus_assign_resources(rootbus);
    + pci_bus_add_devices(rootbus);
    return 0;
    }

    diff --git a/arch/sparc/kernel/pcic.c b/arch/sparc/kernel/pcic.c
    index 6cc78c2..7a82fe2 100644
    --- a/arch/sparc/kernel/pcic.c
    +++ b/arch/sparc/kernel/pcic.c
    @@ -391,6 +391,8 @@ static void __init pcic_pbm_scan_bus(struct linux_pcic *pcic)
    struct linux_pbm_info *pbm = &pcic->pbm;

    pbm->pci_bus = pci_scan_bus(pbm->pci_first_busno, &pcic_ops, pbm);
    + if (pbm->pci_bus)
    + pci_bus_add_devices(pbm->pci_bus);
    #if 0 /* deadwood transplanted from sparc64 */
    pci_fill_in_pbm_cookies(pbm->pci_bus, pbm, pbm->prom_node);
    pci_record_assignments(pbm, pbm->pci_bus);
    diff --git a/arch/unicore32/kernel/pci.c b/arch/unicore32/kernel/pci.c
    index 374a055..3d82024 100644
    --- a/arch/unicore32/kernel/pci.c
    +++ b/arch/unicore32/kernel/pci.c
    @@ -266,17 +266,12 @@ static int __init pci_common_init(void)
    pci_fixup_irqs(pci_common_swizzle, pci_puv3_map_irq);

    if (!pci_has_flag(PCI_PROBE_ONLY)) {
    - /*
    - * Size the bridge windows.
    - */
    + /* Size the bridge windows. */
    pci_bus_size_bridges(puv3_bus);
    -
    - /*
    - * Assign resources.
    - */
    + /* Assign resources. */
    pci_bus_assign_resources(puv3_bus);
    }
    -
    + pci_bus_add_devices(puv3_bus);
    return 0;
    }
    subsys_initcall(pci_common_init);
    diff --git a/drivers/pci/hotplug/ibmphp_core.c b/drivers/pci/hotplug/ibmphp_core.c
    index 96c5c72..86e3bfd 100644
    --- a/drivers/pci/hotplug/ibmphp_core.c
    +++ b/drivers/pci/hotplug/ibmphp_core.c
    @@ -738,7 +738,7 @@ static void ibm_unconfigure_device(struct pci_func *func)
    */
    static u8 bus_structure_fixup(u8 busno)
    {
    - struct pci_bus *bus;
    + struct pci_bus *bus, *b;
    struct pci_dev *dev;
    u16 l;

    @@ -765,7 +765,9 @@ static u8 bus_structure_fixup(u8 busno)
    (l != 0x0000) && (l != 0xffff)) {
    debug("%s - Inside bus_structure_fixup()\n",
    __func__);
    - pci_scan_bus(busno, ibmphp_pci_bus->ops, NULL);
    + b = pci_scan_bus(busno, ibmphp_pci_bus->ops, NULL);
    + if (b)
    + pci_bus_add_devices(b);
    break;
    }
    }
    diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
    index 8d2f400..88604f2 100644
    --- a/drivers/pci/probe.c
    +++ b/drivers/pci/probe.c
    @@ -2123,7 +2123,6 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
    b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
    if (b) {
    pci_scan_child_bus(b);
    - pci_bus_add_devices(b);
    } else {
    pci_free_resource_list(&resources);
    }
    --
    1.7.1


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