[RFC PATCH v1 16/22] PCI/asus-wmi: use PCI bus lock to avoid race conditions

[Jiang Liu]

This patch uses PCI bus lock mechanism to avoid race conditions when doing
PCI device hotplug by asum-wmi driver.

Signed-off-by: Jiang Liu <liu...@gmail.com>
---
 drivers/platform/x86/asus-wmi.c |   23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 77aadde..9972bc7 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -533,15 +533,20 @@ static void asus_rfkill_hotplug(struct asus_wmi *asus)
                rfkill_set_sw_state(asus->wlan.rfkill, blocked);
 
        if (asus->hotplug_slot) {
-               bus = pci_find_bus(0, 1);
+               bus = pci_get_bus(0, 1);
                if (!bus) {
                        pr_warn("Unable to find PCI bus 1?\n");
                        goto out_unlock;
                }
 
+               if (pci_bus_lock_states(bus, PCI_BUS_STATE_WORKING)) {
+                       pr_warn("Unable to lock PCI bus 1?\n");
+                       goto out_put_bus;
+               }
+
                if (pci_bus_read_config_dword(bus, 0, PCI_VENDOR_ID, &l)) {
                        pr_err("Unable to read PCI config space?\n");
-                       goto out_unlock;
+                       goto out_unlock_bus;
                }
                absent = (l == 0xffffffff);
 
@@ -552,7 +557,7 @@ static void asus_rfkill_hotplug(struct asus_wmi *asus)
                                absent ? "absent" : "present");
                        pr_warn("skipped wireless hotplug as probably "
                                "inappropriate for this model\n");
-                       goto out_unlock;
+                       goto out_unlock_bus;
                }
 
                if (!blocked) {
@@ -560,7 +565,7 @@ static void asus_rfkill_hotplug(struct asus_wmi *asus)
                        if (dev) {
                                /* Device already present */
                                pci_dev_put(dev);
-                               goto out_unlock;
+                               goto out_unlock_bus;
                        }
                        dev = pci_scan_single_device(bus, 0);
                        if (dev) {
@@ -575,6 +580,11 @@ static void asus_rfkill_hotplug(struct asus_wmi *asus)
                                pci_dev_put(dev);
                        }
                }
+
+out_unlock_bus:
+               pci_bus_unlock(bus);
+out_put_bus:
+               pci_bus_put(bus);
        }
 
 out_unlock:
@@ -670,7 +680,7 @@ static void asus_hotplug_work(struct work_struct *work)
 static int asus_setup_pci_hotplug(struct asus_wmi *asus)
 {
        int ret = -ENOMEM;
-       struct pci_bus *bus = pci_find_bus(0, 1);
+       struct pci_bus *bus = pci_get_bus(0, 1);
 
        if (!bus) {
                pr_err("Unable to find wifi PCI bus\n");
@@ -705,6 +715,8 @@ static int asus_setup_pci_hotplug(struct asus_wmi *asus)
                goto error_register;
        }
 
+       pci_bus_put(bus);
+
        return 0;
 
 error_register:
@@ -715,6 +727,7 @@ error_info:
 error_slot:
        destroy_workqueue(asus->hotplug_workqueue);
 error_workqueue:
+       pci_bus_put(bus);
        return ret;
 }
 
-- 
1.7.9.5

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