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

From: Jiang Liu
Date: Tue Aug 07 2012 - 12:20:56 EST


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 <liuj97@xxxxxxxxx>
---
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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