ACPI / power: Avoid maybe-uninitialized warning
authorArnd Bergmann <>
Wed, 19 Apr 2017 17:47:04 +0000 (19:47 +0200)
committerRafael J. Wysocki <>
Wed, 19 Apr 2017 20:46:10 +0000 (22:46 +0200)
gcc -O2 cannot always prove that the loop in acpi_power_get_inferred_state()
is enterered at least once, so it assumes that cur_state might not get

drivers/acpi/power.c: In function 'acpi_power_get_inferred_state':
drivers/acpi/power.c:222:9: error: 'cur_state' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This sets the variable to zero at the start of the loop, to ensure that
there is well-defined behavior even for an empty list. This gets rid of
the warning.

The warning first showed up when the -Os flag got removed in a bug fix
patch in linux-4.11-rc5.

I would suggest merging this addon patch on top of that bug fix to avoid
introducing a new warning in the stable kernels.

Fixes: 61b79e16c68d (ACPI: Fix incompatibility with mcount-based function graph tracing)
Cc: All applicable <>
Signed-off-by: Arnd Bergmann <>
Signed-off-by: Rafael J. Wysocki <>

index fcd4ce6f78d5d387080343d96738c3b7275d0324..1c2b846c577604d0b471e87d19cecea6caa286f9 100644 (file)
@@ -200,6 +200,7 @@ static int acpi_power_get_list_state(struct list_head *list, int *state)
                return -EINVAL;
        /* The state of the list is 'on' IFF all resources are 'on'. */
+       cur_state = 0;
        list_for_each_entry(entry, list, node) {
                struct acpi_power_resource *resource = entry->resource;
                acpi_handle handle = resource->device.handle;