hwmon: (asus_atk0110) Don't load if ACPI resources aren't enforced
When the user passes the kernel parameter acpi_enforce_resources=lax,
the ACPI resources are no longer protected, so a native driver can
make use of them. In that case, we do not want the asus_atk0110 to be
loaded. Unfortunately, this driver loads automatically due to its
MODULE_DEVICE_TABLE, so the user ends up with two drivers loaded for
the same device - this is bad.
So I suggest that we prevent the asus_atk0110 driver from loading if
acpi_enforce_resources=lax.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Luca Tettamanti <kronos.it@gmail.com>
Cc: Len Brown <lenb@kernel.org>
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 4bc1c41..78418ce 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -1207,6 +1207,15 @@
EXPORT_SYMBOL(acpi_check_mem_region);
/*
+ * Let drivers know whether the resource checks are effective
+ */
+int acpi_resources_are_enforced(void)
+{
+ return acpi_enforce_resources == ENFORCE_RESOURCES_STRICT;
+}
+EXPORT_SYMBOL(acpi_resources_are_enforced);
+
+/*
* Acquire a spinlock.
*
* handle is a pointer to the spinlock_t.
diff --git a/drivers/hwmon/asus_atk0110.c b/drivers/hwmon/asus_atk0110.c
index 16c4202..653db1b 100644
--- a/drivers/hwmon/asus_atk0110.c
+++ b/drivers/hwmon/asus_atk0110.c
@@ -1411,6 +1411,13 @@
{
int ret;
+ /* Make sure it's safe to access the device through ACPI */
+ if (!acpi_resources_are_enforced()) {
+ pr_err("atk: Resources not safely usable due to "
+ "acpi_enforce_resources kernel parameter\n");
+ return -EBUSY;
+ }
+
ret = acpi_bus_register_driver(&atk_driver);
if (ret)
pr_info("atk: acpi_bus_register_driver failed: %d\n", ret);
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 3da73f5..2c60f1f 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -248,6 +248,8 @@
int acpi_check_mem_region(resource_size_t start, resource_size_t n,
const char *name);
+int acpi_resources_are_enforced(void);
+
#ifdef CONFIG_PM_SLEEP
void __init acpi_no_s4_hw_signature(void);
void __init acpi_old_suspend_ordering(void);