hwmon: (ams) Fix locking issues

Use a separate mutex to serialize input device creation/removal,
otheriwse we deadlock if we try to remove input device while it is
being polled. Also do not take ams_info.lock when it is not needed.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 5 insertions, 13 deletions

diff --git a/drivers/hwmon/ams/ams-pmu.c b/drivers/hwmon/ams/ams-pmu.c
index 9463e9768f6f..fb18b3d3162b 100644
--- a/drivers/hwmon/ams/ams-pmu.c
+++ b/drivers/hwmon/ams/ams-pmu.c
@@ -149,8 +149,6 @@ int __init ams_pmu_init(struct device_node *np)
         const u32 *prop;
         int result;
 
-        mutex_lock(&ams_info.lock);
-
         /* Set implementation stuff */
         ams_info.of_node = np;
         ams_info.exit = ams_pmu_exit;
@@ -161,10 +159,9 @@ int __init ams_pmu_init(struct device_node *np)
 
         /* Get PMU command, should be 0x4e, but we can never know */
         prop = of_get_property(ams_info.of_node, "reg", NULL);
-        if (!prop) {
-                result = -ENODEV;
-                goto exit;
-        }
+        if (!prop)
+                return -ENODEV;
+
         ams_pmu_cmd = ((*prop) >> 8) & 0xff;
 
         /* Disable interrupts */
@@ -175,7 +172,7 @@ int __init ams_pmu_init(struct device_node *np)
 
         result = ams_sensor_attach();
         if (result < 0)
-                goto exit;
+                return result;
 
         /* Set default values */
         ams_pmu_set_register(AMS_FF_LOW_LIMIT, 0x15);
@@ -198,10 +195,5 @@ int __init ams_pmu_init(struct device_node *np)
 
         printk(KERN_INFO "ams: Found PMU based motion sensor\n");
 
-        result = 0;
-
-exit:
-        mutex_unlock(&ams_info.lock);
-
-        return result;
+        return 0;
 }