[Xen-devel] [PATCH v3, part2 02/20] PCI, core: use hotplug-safe iterators to walk PCI buses

[Jiang Liu <liuj97@xxxxxxxxx>]

Enhance PCI core to use hotplug-safe iterators to walk PCI buses.

In other words, replace pci_find_bus(), pci_find_next_bus() and
pci_root_buses with pci_bus_exists(), pci_get_bus(), pci_get_next_bus()
and pci_get_next_root_bus() etc.

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
Acked-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
---
 drivers/pci/pci-sysfs.c    |  2 +-
 drivers/pci/pcie/pme.c     |  5 +++--
 drivers/pci/probe.c        | 15 +++++++++------
 drivers/pci/setup-bus.c    | 14 ++++++--------
 drivers/pci/xen-pcifront.c |  3 ++-
 5 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 403da60..e2da5f3 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -296,7 +296,7 @@ static ssize_t bus_rescan_store(struct bus_type *bus, const 
char *buf,
 
        if (val) {
                mutex_lock(&pci_remove_rescan_mutex);
-               while ((b = pci_find_next_bus(b)) != NULL)
+               for_each_pci_root_bus(b)
                        pci_rescan_bus(b);
                mutex_unlock(&pci_remove_rescan_mutex);
        }
diff --git a/drivers/pci/pcie/pme.c b/drivers/pci/pcie/pme.c
index 795db1f..1ed38a3 100644
--- a/drivers/pci/pcie/pme.c
+++ b/drivers/pci/pcie/pme.c
@@ -132,7 +132,7 @@ static bool pcie_pme_from_pci_bridge(struct pci_bus *bus, 
u8 devfn)
 static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
 {
        u8 busnr = req_id >> 8, devfn = req_id & 0xff;
-       struct pci_bus *bus;
+       struct pci_bus *bus = NULL;
        struct pci_dev *dev;
        bool found = false;
 
@@ -161,7 +161,7 @@ static void pcie_pme_handle_request(struct pci_dev *port, 
u16 req_id)
        }
 
        /* Second, find the bus the source device is on. */
-       bus = pci_find_bus(pci_domain_nr(port->bus), busnr);
+       bus = pci_get_bus(pci_domain_nr(port->bus), busnr);
        if (!bus)
                goto out;
 
@@ -206,6 +206,7 @@ static void pcie_pme_handle_request(struct pci_dev *port, 
u16 req_id)
        }
 
  out:
+       pci_bus_put(bus);
        if (!found)
                dev_dbg(&port->dev, "Spurious native PME interrupt!\n");
 }
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1004a05..7c34362 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -752,7 +752,7 @@ static void pci_fixup_parent_subordinate_busnr(struct 
pci_bus *child, int max)
  */
 int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int 
pass)
 {
-       struct pci_bus *child;
+       struct pci_bus *child = NULL;
        int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS);
        u32 buses, i, j = 0;
        u16 bctl;
@@ -804,7 +804,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev 
*dev, int max, int pass)
                 * However, we continue to descend down the hierarchy and
                 * scan remaining child buses.
                 */
-               child = pci_find_bus(pci_domain_nr(bus), secondary);
+               child = pci_get_bus(pci_domain_nr(bus), secondary);
                if (!child) {
                        child = pci_add_new_bus(bus, dev, secondary);
                        if (!child)
@@ -812,6 +812,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev 
*dev, int max, int pass)
                        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);
@@ -843,12 +844,13 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev 
*dev, int max, int pass)
                /* 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);
+               child = pci_get_bus(pci_domain_nr(bus), max+1);
                if (!child) {
                        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)
@@ -893,8 +895,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev 
*dev, int max, int pass)
                         */
                        for (i=0; i<CARDBUS_RESERVE_BUSNR; i++) {
                                struct pci_bus *parent = bus;
-                               if (pci_find_bus(pci_domain_nr(bus),
-                                                       max+i+1))
+                               if (pci_bus_exists(pci_domain_nr(bus), max+i+1))
                                        break;
                                while (parent->parent) {
                                        if ((!pcibios_assign_all_busses()) &&
@@ -949,6 +950,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev 
*dev, int max, int pass)
 
 out:
        pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);
+       pci_bus_put(child);
 
        return max;
 }
@@ -1710,10 +1712,11 @@ struct pci_bus *pci_create_root_bus(struct device 
*parent, int bus,
        if (!b)
                return NULL;
 
-       b2 = pci_find_bus(pci_domain_nr(b), bus);
+       b2 = pci_get_bus(pci_domain_nr(b), bus);
        if (b2) {
                /* If we already got to this bus through a different bridge, 
ignore it */
                dev_dbg(&b2->dev, "bus already known\n");
+               pci_bus_put(b2);
                goto err_out;
        }
 
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 16abaaa..9a3e3f7 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1317,12 +1317,10 @@ static int __init pci_bus_get_depth(struct pci_bus *bus)
 }
 static int __init pci_get_max_depth(void)
 {
-       int depth = 0;
+       int ret, depth = 0;
        struct pci_bus *bus;
 
-       list_for_each_entry(bus, &pci_root_buses, node) {
-               int ret;
-
+       for_each_pci_root_bus(bus) {
                ret = pci_bus_get_depth(bus);
                if (ret > depth)
                        depth = ret;
@@ -1423,11 +1421,11 @@ again:
                add_list = &realloc_head;
        /* Depth first, calculate sizes and alignments of all
           subordinate buses. */
-       list_for_each_entry(bus, &pci_root_buses, node)
+       for_each_pci_root_bus(bus)
                __pci_bus_size_bridges(bus, add_list);
 
        /* Depth last, allocate resources and update the hardware. */
-       list_for_each_entry(bus, &pci_root_buses, node)
+       for_each_pci_root_bus(bus)
                __pci_bus_assign_resources(bus, add_list, &fail_head);
        if (add_list)
                BUG_ON(!list_empty(add_list));
@@ -1480,11 +1478,11 @@ again:
 
 enable_and_dump:
        /* Depth last, update the hardware. */
-       list_for_each_entry(bus, &pci_root_buses, node)
+       for_each_pci_root_bus(bus)
                pci_enable_bridges(bus);
 
        /* dump the resource on buses */
-       list_for_each_entry(bus, &pci_root_buses, node)
+       for_each_pci_root_bus(bus)
                pci_bus_dump_resources(bus);
 }
 
diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 966abc6..816cf94 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -522,7 +522,7 @@ static int pcifront_rescan_root(struct pcifront_device 
*pdev,
        dev_info(&pdev->xdev->dev, "Rescanning PCI Frontend Bus %04x:%02x\n",
                 domain, bus);
 
-       b = pci_find_bus(domain, bus);
+       b = pci_get_bus(domain, bus);
        if (!b)
                /* If the bus is unknown, create it. */
                return pcifront_scan_root(pdev, domain, bus);
@@ -534,6 +534,7 @@ static int pcifront_rescan_root(struct pcifront_device 
*pdev,
 
        /* Create SysFS and notify udev of the devices. Aka: "going live" */
        pci_bus_add_devices(b);
+       pci_bus_put(b);
 
        return err;
 }
-- 
1.8.1.2


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