[PATCH] ACPI: battery: fix battery->alarm is updated when it is not supported

[PATCH] ACPI: battery: fix battery->alarm is updated when it is not supported

[Alex Hung]

battery alarm is checked whether BIOS supports it before past to BIOS;
however, the value is updatd without being checked. This causes alarm return
an incorrect value that never represents an actual state BIOS is in.

Signed-off-by: Alex Hung <alex.hung@canonical.com>
---
 drivers/acpi/battery.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 86933ca..14548e8 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -535,7 +535,8 @@ static ssize_t acpi_battery_alarm_store(struct device *dev,
 {
 	unsigned long x;
 	struct acpi_battery *battery = to_acpi_battery(dev_get_drvdata(dev));
-	if (sscanf(buf, "%ld\n", &x) == 1)
+	if (sscanf(buf, "%ld\n", &x) == 1 &&
+		test_bit(ACPI_BATTERY_ALARM_PRESENT, &battery->flags))
 		battery->alarm = x/1000;
 	if (acpi_battery_present(battery))
 		acpi_battery_set_alarm(battery);
@@ -805,7 +806,8 @@ static ssize_t acpi_battery_write_alarm(struct file *file,
 		goto end;
 	}
 	alarm_string[count] = '\0';
-	battery->alarm = simple_strtol(alarm_string, NULL, 0);
+	if (test_bit(ACPI_BATTERY_ALARM_PRESENT, &battery->flags))
+		battery->alarm = simple_strtol(alarm_string, NULL, 0);
 	result = acpi_battery_set_alarm(battery);
       end:
 	if (!result)
-- 
1.7.0.4

Re: [PATCH] ACPI: battery: fix battery->alarm is updated when it is not supported

[Alex Hung]

Hi,

I haven't received any feedback for the patch. I am wondering whether I 
can improve the patch or the extra check is not needed.

Any suggestion is the most appreciated.

Best Regards,
Alex Hung

On 05/20/2012 08:05 PM, Alex Hung wrote:
> battery alarm is checked whether BIOS supports it before past to BIOS;
> however, the value is updatd without being checked. This causes alarm return
> an incorrect value that never represents an actual state BIOS is in.
>
> Signed-off-by: Alex Hung <alex.hung@canonical.com>
> ---
>   drivers/acpi/battery.c |    6 ++++--
>   1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index 86933ca..14548e8 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -535,7 +535,8 @@ static ssize_t acpi_battery_alarm_store(struct device *dev,
>   {
>   	unsigned long x;
>   	struct acpi_battery *battery = to_acpi_battery(dev_get_drvdata(dev));
> -	if (sscanf(buf, "%ld\n", &x) == 1)
> +	if (sscanf(buf, "%ld\n", &x) == 1 &&
> +		test_bit(ACPI_BATTERY_ALARM_PRESENT, &battery->flags))
>   		battery->alarm = x/1000;
>   	if (acpi_battery_present(battery))
>   		acpi_battery_set_alarm(battery);
> @@ -805,7 +806,8 @@ static ssize_t acpi_battery_write_alarm(struct file *file,
>   		goto end;
>   	}
>   	alarm_string[count] = '\0';
> -	battery->alarm = simple_strtol(alarm_string, NULL, 0);
> +	if (test_bit(ACPI_BATTERY_ALARM_PRESENT, &battery->flags))
> +		battery->alarm = simple_strtol(alarm_string, NULL, 0);
>   	result = acpi_battery_set_alarm(battery);
>         end:
>   	if (!result)
>