greybus: power_supply: invalidate cache at update request

When we receive a update request we shall not trust the cache mechanism
and for that we need a way to invalidate the cache. Add a field that
will control the cache status and refactor the code to check if cache is
valid in a helper function.

This will fix the scenario where an update request is received within
the cache expiration time after a previous update as happened and would
be ignored.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/power_supply.c b/drivers/staging/greybus/power_supply.c
index 3d6f81017d984f34d73ea06e02374196d833bdaf..199a19a634b6c13ec7ea75a67cb9d2261b0b1150 100644 (file)
--- a/drivers/staging/greybus/power_supply.c
+++ b/drivers/staging/greybus/power_supply.c
@@ -45,6 +45,7 @@ struct gb_power_supply {
        u8                              properties_count;
        u8                              properties_count_str;
        unsigned long                   last_update;
+       u8                              cache_invalid;
        unsigned int                    update_interval;
        bool                            changed;
        struct gb_power_supply_prop     *props;
@@ -636,15 +637,28 @@ static int _gb_power_supply_property_get(struct gb_power_supply *gbpsy,
        return 0;
 }
 
-static int gb_power_supply_status_get(struct gb_power_supply *gbpsy)
+static int is_cache_valid(struct gb_power_supply *gbpsy)
 {
-       int ret = 0;
-       int i;
+       /* check if cache is good enough or it has expired */
+       if (gbpsy->cache_invalid) {
+               gbpsy->cache_invalid = 0;
+               return 0;
+       }
 
-       /* check if cache is good enough */
        if (gbpsy->last_update &&
            time_is_after_jiffies(gbpsy->last_update +
                                  msecs_to_jiffies(cache_time)))
+               return 1;
+
+       return 0;
+}
+
+static int gb_power_supply_status_get(struct gb_power_supply *gbpsy)
+{
+       int ret = 0;
+       int i;
+
+       if (is_cache_valid(gbpsy))
                return 0;
 
        for (i = 0; i < gbpsy->properties_count; i++) {
@@ -987,8 +1001,15 @@ static int gb_supplies_request_handler(struct gb_operation *op)
                goto out_unlock;
        }
 
-       if (event & GB_POWER_SUPPLY_UPDATE)
+       if (event & GB_POWER_SUPPLY_UPDATE) {
+               /*
+                * we need to make sure we invalidate cache, if not no new
+                * values for the properties will be fetch and the all propose
+                * of this event is missed
+                */
+               gbpsy->cache_invalid = 1;
                gb_power_supply_status_update(gbpsy);
+       }
 
 out_unlock:
        mutex_unlock(&supplies->supplies_lock);