The backlight class does all the locking needed for sysfs access, but
offers no API to interface to that locking without an layer violation.
Since we need to mutex-lock procfs access, implement in-driver locking for
brightness. It will go away the day thinkpad-acpi procfs goes away, or the
backlight class gives us a way to use its locks without a layer violation.
Signed-off-by: Henrique de Moraes Holschuh <hmh@xxxxxxxxxx>
---
drivers/misc/thinkpad_acpi.c | 35 ++++++++++++++++++++++++++++-------
1 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index 01bed93..f15a58f 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -3000,12 +3000,16 @@ static struct backlight_ops ibm_backlight_data = {
.update_status = brightness_update_status,
};
+static struct mutex brightness_mutex;
+
static int __init brightness_init(struct ibm_init_struct *iibm)
{
int b;
vdbg_printk(TPACPI_DBG_INIT, "initializing brightness subdriver\n");
+ mutex_init(&brightness_mutex);
+
if (!brightness_mode) {
if (thinkpad_id.vendor == PCI_VENDOR_ID_LENOVO)
brightness_mode = 2;
@@ -3092,27 +3096,44 @@ static int brightness_get(struct backlight_device *bd)
static int brightness_set(int value)
{
- int cmos_cmd, inc, i;
- int current_value = brightness_get(NULL);
+ int cmos_cmd, inc, i, res;
+ int current_value;
if (value > 7)
return -EINVAL;
+ res = mutex_lock_interruptible(&brightness_mutex);
+ if (res < 0)
+ return res;
+
+ current_value = brightness_get(NULL);
+ if (current_value < 0) {
+ res = current_value;
+ goto errout;
+ }
+
cmos_cmd = value > current_value ?
TP_CMOS_BRIGHTNESS_UP :
TP_CMOS_BRIGHTNESS_DOWN;
inc = value > current_value ? 1 : -1;
+ res = 0;
for (i = current_value; i != value; i += inc) {
if ((brightness_mode & 2) &&
- issue_thinkpad_cmos_command(cmos_cmd))
- return -EIO;
+ issue_thinkpad_cmos_command(cmos_cmd)) {
+ res = -EIO;
+ goto errout;
+ }
if ((brightness_mode & 1) &&
- !acpi_ec_write(brightness_offset, i + inc))
- return -EIO;
+ !acpi_ec_write(brightness_offset, i + inc)) {
+ res = -EIO;
+ goto errout;;
+ }
}
- return 0;
+errout:
+ mutex_unlock(&brightness_mutex);
+ return res;
}
static int brightness_read(char *p)
--
1.5.2.1
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