ACPI/PCI: Fix possible race condition on _OSC evaluation

Fix possible race condition on _OSC evaluation.

Current _OSC evaluation code has possible race condition because it
maniputes osc_data linked list or its contents without any lock
mechanism.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 20 insertions, 8 deletions

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 89a2f0fa10f9..14848bf95e82 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -35,6 +35,8 @@ struct acpi_osc_args {
         u32 query_result;
 };
 
+static DEFINE_MUTEX(pci_acpi_lock);
+
 static struct acpi_osc_data *acpi_get_osc_data(acpi_handle handle)
 {
         struct acpi_osc_data *data;
@@ -131,10 +133,12 @@ static acpi_status acpi_query_osc(acpi_handle handle,
         if (ACPI_FAILURE(status))
                 return status;
 
+        mutex_lock(&pci_acpi_lock);
         osc_data = acpi_get_osc_data(handle);
         if (!osc_data) {
                 printk(KERN_ERR "acpi osc data array is full\n");
-                return AE_ERROR;
+                status = AE_ERROR;
+                goto out;
         }
 
         /* do _OSC query for all possible controls */
@@ -149,7 +153,8 @@ static acpi_status acpi_query_osc(acpi_handle handle,
                 osc_data->query_result = osc_args.query_result;
                 osc_data->is_queried = 1;
         }
-
+out:
+        mutex_unlock(&pci_acpi_lock);
         return status;
 }
 
@@ -190,19 +195,25 @@ acpi_status pci_osc_control_set(acpi_handle handle, u32 flags)
         if (ACPI_FAILURE(status))
                 return status;
 
+        mutex_lock(&pci_acpi_lock);
         osc_data = acpi_get_osc_data(handle);
         if (!osc_data) {
                 printk(KERN_ERR "acpi osc data array is full\n");
-                return AE_ERROR;
+                status = AE_ERROR;
+                goto out;
         }
 
         ctrlset = (flags & OSC_CONTROL_MASKS);
-        if (!ctrlset)
-                return AE_TYPE;
+        if (!ctrlset) {
+                status = AE_TYPE;
+                goto out;
+        }
 
         if (osc_data->is_queried &&
-            ((osc_data->query_result & ctrlset) != ctrlset))
-                return AE_SUPPORT;
+            ((osc_data->query_result & ctrlset) != ctrlset)) {
+                status = AE_SUPPORT;
+                goto out;
+        }
 
         control_set = osc_data->control_set | ctrlset;
         osc_args.capbuf[OSC_QUERY_TYPE] = 0;
@@ -211,7 +222,8 @@ acpi_status pci_osc_control_set(acpi_handle handle, u32 flags)
         status = acpi_run_osc(handle, &osc_args);
         if (ACPI_SUCCESS(status))
                 osc_data->control_set = control_set;
-
+out:
+        mutex_unlock(&pci_acpi_lock);
         return status;
 }
 EXPORT_SYMBOL(pci_osc_control_set);