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    Subject[RFC PATCH v1 09/22] PCI: enhance PCI probe logic to support PCI bus lock mechanism
    Date
    This patch enhances PCI probe logic to support PCI bus lock mechanism.

    Signed-off-by: Jiang Liu <liuj97@gmail.com>
    ---
    drivers/pci/probe.c | 65 +++++++++++++++++++++++++++++++++++++++------------
    1 file changed, 50 insertions(+), 15 deletions(-)

    diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
    index 1f64e8d..e6b40d0 100644
    --- a/drivers/pci/probe.c
    +++ b/drivers/pci/probe.c
    @@ -460,6 +460,8 @@ static struct pci_bus * pci_alloc_bus(void)
    b->max_bus_speed = PCI_SPEED_UNKNOWN;
    b->cur_bus_speed = PCI_SPEED_UNKNOWN;
    device_initialize(&b->dev);
    + atomic_set(&b->state,
    + PCI_BUS_STATE_INITIALIZED | PCI_BUS_STATE_LOCK);
    }
    return b;
    }
    @@ -753,14 +755,21 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
    * However, we continue to descend down the hierarchy and
    * scan remaining child buses.
    */
    - child = pci_find_bus(pci_domain_nr(bus), secondary);
    - if (!child) {
    + child = __pci_get_and_lock_bus(pci_domain_nr(bus), secondary,
    + PCI_BUS_STATE_MASK);
    + if (child) {
    + if (pci_bus_get_state(child) > PCI_BUS_STATE_WORKING) {
    + pci_unlock_and_put_bus(child);
    + goto out;
    + }
    + } else {
    child = pci_add_new_bus(bus, dev, secondary);
    if (!child)
    goto out;
    child->primary = primary;
    pci_bus_insert_busn_res(child, secondary, subordinate);
    child->bridge_ctl = bctl;
    + pci_bus_get(child);
    }

    cmax = pci_scan_child_bus(child);
    @@ -792,12 +801,19 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
    /* Prevent assigning a bus number that already exists.
    * This can happen when a bridge is hot-plugged, so in
    * this case we only re-scan this bus. */
    - child = pci_find_bus(pci_domain_nr(bus), max+1);
    - if (!child) {
    + child = __pci_get_and_lock_bus(pci_domain_nr(bus), secondary,
    + PCI_BUS_STATE_MASK);
    + if (child) {
    + if (pci_bus_get_state(child) > PCI_BUS_STATE_WORKING) {
    + pci_unlock_and_put_bus(child);
    + goto out;
    + }
    + } else {
    child = pci_add_new_bus(bus, dev, ++max);
    if (!child)
    goto out;
    pci_bus_insert_busn_res(child, max, 0xff);
    + pci_bus_get(child);
    }
    buses = (buses & 0xff000000)
    | ((unsigned int)(child->primary) << 0)
    @@ -896,6 +912,8 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
    bus = bus->parent;
    }

    + pci_unlock_and_put_bus(child);
    +
    out:
    pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);

    @@ -1605,11 +1623,14 @@ unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus)
    * After performing arch-dependent fixup of the bus, look behind
    * all PCI-to-PCI bridges on this bus.
    */
    - if (!bus->is_added) {
    + if (pci_bus_get_state(bus) < PCI_BUS_STATE_WORKING) {
    dev_dbg(&bus->dev, "fixups for bus\n");
    pcibios_fixup_bus(bus);
    - if (pci_is_root_bus(bus))
    + if (pci_is_root_bus(bus)) {
    + pci_bus_change_state(bus, PCI_BUS_STATE_REGISTERED,
    + PCI_BUS_STATE_WORKING, false);
    bus->is_added = 1;
    + }
    }

    for (pass=0; pass < 2; pass++)
    @@ -1630,6 +1651,11 @@ unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus)
    return max;
    }

    +/*
    + * Create a PCI root bus and return with the new root bus locked.
    + * Caller needs to call pci_bus_unlock() to unlock the new root bus after
    + * scanning and configuring children under the new root bus.
    + */
    struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
    struct pci_ops *ops, void *sysdata, struct list_head *resources)
    {
    @@ -1716,6 +1742,9 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
    list_add_tail(&b->node, &pci_root_buses);
    up_write(&pci_bus_sem);

    + pci_bus_change_state(b, PCI_BUS_STATE_INITIALIZED,
    + PCI_BUS_STATE_REGISTERED, false);
    +
    return b;

    class_dev_reg_err:
    @@ -1724,7 +1753,7 @@ class_dev_reg_err:
    bridge_dev_reg_err:
    kfree(bridge);
    err_out:
    - kfree(b);
    + pci_unlock_and_put_bus(b);
    return NULL;
    }

    @@ -1827,6 +1856,8 @@ struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
    pci_bus_update_busn_res_end(b, max);

    pci_bus_add_devices(b);
    + pci_bus_unlock(b);
    +
    return b;
    }
    EXPORT_SYMBOL(pci_scan_root_bus);
    @@ -1842,10 +1873,12 @@ struct pci_bus * __devinit pci_scan_bus_parented(struct device *parent,
    pci_add_resource(&resources, &iomem_resource);
    pci_add_resource(&resources, &busn_resource);
    b = pci_create_root_bus(parent, bus, ops, sysdata, &resources);
    - if (b)
    + if (b) {
    pci_scan_child_bus(b);
    - else
    + pci_bus_unlock(b);
    + } else {
    pci_free_resource_list(&resources);
    + }
    return b;
    }
    EXPORT_SYMBOL(pci_scan_bus_parented);
    @@ -1863,6 +1896,7 @@ struct pci_bus * __devinit pci_scan_bus(int bus, struct pci_ops *ops,
    if (b) {
    pci_scan_child_bus(b);
    pci_bus_add_devices(b);
    + pci_bus_unlock(b);
    } else {
    pci_free_resource_list(&resources);
    }
    @@ -1884,14 +1918,15 @@ EXPORT_SYMBOL(pci_scan_bus);
    */
    unsigned int __ref pci_rescan_bus_bridge_resize(struct pci_dev *bridge)
    {
    - unsigned int max;
    + unsigned int max = -1;
    struct pci_bus *bus = bridge->subordinate;

    - max = pci_scan_child_bus(bus);
    -
    - pci_assign_unassigned_bridge_resources(bridge);
    -
    - pci_bus_add_devices(bus);
    + if (pci_bus_lock_states(bus, PCI_BUS_STATE_WORKING) > 0) {
    + max = pci_scan_child_bus(bus);
    + pci_assign_unassigned_bridge_resources(bridge);
    + pci_bus_add_devices(bus);
    + pci_bus_unlock(bus);
    + }

    return max;
    }
    --
    1.7.9.5


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