staging: binder: Change binder mutex to rtmutex.

Surfaceflinger uses binder heavily to receive/send frames from applications
while compositing the screen. Change the binder mutex to an rt mutex to minimize
instances where high priority surfaceflinger binder work is blocked by lower
priority binder ipc.

Signed-off-by: Riley Andrews <riandrews@google.com>
Change-Id: I086a715267648448f0c5f62b037a3093d1079a79

diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index d4e5290019344f2797ab6c2c892500419b4f4d42..9c821f398cad6424c3e8ddb2dac21da61b06126d 100644 (file)
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -26,6 +26,7 @@
 #include <linux/miscdevice.h>
 #include <linux/mm.h>
 #include <linux/module.h>
+#include <linux/rtmutex.h>
 #include <linux/mutex.h>
 #include <linux/nsproxy.h>
 #include <linux/poll.h>
@@ -42,7 +43,7 @@
 #include "binder.h"
 #include "binder_trace.h"
 
-static DEFINE_MUTEX(binder_main_lock);
+static DEFINE_RT_MUTEX(binder_main_lock);
 static DEFINE_MUTEX(binder_deferred_lock);
 static DEFINE_MUTEX(binder_mmap_lock);
 
@@ -420,14 +421,14 @@ static long task_close_fd(struct binder_proc *proc, unsigned int fd)
 static inline void binder_lock(const char *tag)
 {
        trace_binder_lock(tag);
-       mutex_lock(&binder_main_lock);
+       rt_mutex_lock(&binder_main_lock);
        trace_binder_locked(tag);
 }
 
 static inline void binder_unlock(const char *tag)
 {
        trace_binder_unlock(tag);
-       mutex_unlock(&binder_main_lock);
+       rt_mutex_unlock(&binder_main_lock);
 }
 
 static void binder_set_nice(long nice)