ACPI / scan: not cache _SUN value in struct acpi_device_pnp

The _SUN device indentification object is not guaranteed to return
the same value every time it is executed, so we should not cache its
return value, but rather execute it every time as needed.  If it is
cached, an incorrect stale value may be used in some situations.

This issue was exposed by commit 202317a573b2 (ACPI / scan: Add
acpi_device objects for all device nodes in the namespace).  Fix it
by avoiding to cache the return value of _SUN.

Fixes: 202317a573b2 (ACPI / scan: Add acpi_device objects for all device nodes in the namespace)
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 9a9298994e262cdbb17ee883009bbae6d2d082d3..3bf7764659a4f5643557eb2aee4b5b327da4f88f 100644 (file)
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -667,8 +667,14 @@ static ssize_t
 acpi_device_sun_show(struct device *dev, struct device_attribute *attr,
                     char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);
+       acpi_status status;
+       unsigned long long sun;
+
+       status = acpi_evaluate_integer(acpi_dev->handle, "_SUN", NULL, &sun);
+       if (ACPI_FAILURE(status))
+               return -ENODEV;
 
-       return sprintf(buf, "%lu\n", acpi_dev->pnp.sun);
+       return sprintf(buf, "%llu\n", sun);
 }
 static DEVICE_ATTR(sun, 0444, acpi_device_sun_show, NULL);
 
@@ -690,7 +696,6 @@ static int acpi_device_setup_files(struct acpi_device *dev)
 {
        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
        acpi_status status;
-       unsigned long long sun;
        int result = 0;
 
        /*
@@ -731,14 +736,10 @@ static int acpi_device_setup_files(struct acpi_device *dev)
        if (dev->pnp.unique_id)
                result = device_create_file(&dev->dev, &dev_attr_uid);
 
-       status = acpi_evaluate_integer(dev->handle, "_SUN", NULL, &sun);
-       if (ACPI_SUCCESS(status)) {
-               dev->pnp.sun = (unsigned long)sun;
+       if (acpi_has_method(dev->handle, "_SUN")) {
                result = device_create_file(&dev->dev, &dev_attr_sun);
                if (result)
                        goto end;
-       } else {
-               dev->pnp.sun = (unsigned long)-1;
        }
 
        if (acpi_has_method(dev->handle, "_STA")) {

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index bcfd808b1098e81e410310e33582d814274188b8..c1c9de19edbe8abc62f2508bf9a7723bd9027d08 100644 (file)
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -246,7 +246,6 @@ struct acpi_device_pnp {
        acpi_device_name device_name;   /* Driver-determined */
        acpi_device_class device_class; /*        "          */
        union acpi_object *str_obj;     /* unicode string for _STR method */
-       unsigned long sun;              /* _SUN */
 };
 
 #define acpi_device_bid(d)     ((d)->pnp.bus_id)