rfkill: document the rfkill struct locking (v2)

Reorder fields in struct rfkill and add comments to make it clear
which fields are protected by rfkill->mutex.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/rfkill.h b/include/linux/rfkill.h
index c5f6e54ec6ae..741d1a62cc3f 100644
--- a/include/linux/rfkill.h
+++ b/include/linux/rfkill.h
@@ -68,7 +68,8 @@ enum rfkill_state {
  * @user_claim_unsupported: Whether the hardware supports exclusive
  *      RF-kill control by userspace. Set this before registering.
  * @user_claim: Set when the switch is controlled exlusively by userspace.
- * @mutex: Guards switch state transitions
+ * @mutex: Guards switch state transitions.  It serializes callbacks
+ *      and also protects the state.
  * @data: Pointer to the RF button drivers private data which will be
  *      passed along when toggling radio state.
  * @toggle_radio(): Mandatory handler to control state of the radio.
@@ -89,12 +90,13 @@ struct rfkill {
         const char *name;
         enum rfkill_type type;
 
-        enum rfkill_state state;
         bool user_claim_unsupported;
         bool user_claim;
 
+        /* the mutex serializes callbacks and also protects
+         * the state */
         struct mutex mutex;
-
+        enum rfkill_state state;
         void *data;
         int (*toggle_radio)(void *data, enum rfkill_state state);
         int (*get_state)(void *data, enum rfkill_state *state);