[PATCH 42/49] rc-ir-raw: atomic reads of protocols

From: "David Härdeman" <david@hardeman.nu>
To: linux-media@vger.kernel.org
Cc: m.chehab@samsung.com
Subject: [PATCH 42/49] rc-ir-raw: atomic reads of protocols
Date: Fri, 04 Apr 2014 01:34:48 +0200	[thread overview]
Message-ID: <20140403233448.27099.69654.stgit@zeus.muc.hardeman.nu> (raw)
In-Reply-To: <20140403232420.27099.94872.stgit@zeus.muc.hardeman.nu>

Use atomic reads to avoid having to take a mutex when getting
the bitmask of supported protocols.

Signed-off-by: David Härdeman <david@hardeman.nu>
---
 drivers/media/rc/rc-core-priv.h |    2 +-
 drivers/media/rc/rc-ir-raw.c    |   12 ++++--------
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
index c3de26b..04776e8 100644
--- a/drivers/media/rc/rc-core-priv.h
+++ b/drivers/media/rc/rc-core-priv.h
@@ -29,7 +29,7 @@ enum rc_driver_type {
 struct ir_raw_handler {
 	struct list_head list;
 
-	u64 protocols; /* which are handled by this handler */
+	unsigned protocols; /* which are handled by this handler */
 	int (*decode)(struct rc_dev *dev, struct ir_raw_event event);
 
 	/* These two should only be used by the lirc decoder */
diff --git a/drivers/media/rc/rc-ir-raw.c b/drivers/media/rc/rc-ir-raw.c
index 9631825..bf5215b 100644
--- a/drivers/media/rc/rc-ir-raw.c
+++ b/drivers/media/rc/rc-ir-raw.c
@@ -27,7 +27,7 @@ static LIST_HEAD(ir_raw_client_list);
 static LIST_HEAD(ir_raw_handler_list);
 
 /* protocols supported by the currently loaded decoders */
-static u64 available_protocols;
+static atomic_t available_protocols = ATOMIC_INIT(0);
 
 static int ir_raw_event_thread(void *data)
 {
@@ -251,11 +251,7 @@ EXPORT_SYMBOL_GPL(ir_raw_event_handle);
 /* used internally by the sysfs interface */
 static u64 ir_raw_get_allowed_protocols(struct rc_dev *dev)
 {
-	u64 protocols;
-	mutex_lock(&ir_raw_mutex);
-	protocols = available_protocols;
-	mutex_unlock(&ir_raw_mutex);
-	return protocols;
+	return atomic_read(&available_protocols);
 }
 
 static int change_protocol(struct rc_dev *dev, u64 *rc_type) {
@@ -353,7 +349,7 @@ int ir_raw_handler_register(struct ir_raw_handler *ir_raw_handler)
 	if (ir_raw_handler->raw_register)
 		list_for_each_entry_rcu(raw, &ir_raw_client_list, list)
 			ir_raw_handler->raw_register(raw->dev);
-	available_protocols |= ir_raw_handler->protocols;
+	atomic_set_mask(ir_raw_handler->protocols, &available_protocols);
 	mutex_unlock(&ir_raw_mutex);
 	synchronize_rcu();
 
@@ -370,7 +366,7 @@ void ir_raw_handler_unregister(struct ir_raw_handler *ir_raw_handler)
 	if (ir_raw_handler->raw_unregister)
 		list_for_each_entry_rcu(raw, &ir_raw_client_list, list)
 			ir_raw_handler->raw_unregister(raw->dev);
-	available_protocols &= ~ir_raw_handler->protocols;
+	atomic_clear_mask(ir_raw_handler->protocols, &available_protocols);
 	mutex_unlock(&ir_raw_mutex);
 	synchronize_rcu();
 }

