Bluetooth: Boost timer callback thread priority to high

- Boost timer callback thread priority to high for
  getting alarm callback with priority during a2dp
  music playback.

- Media task/btu/hci/event threads are all high priority
  but actual callback thread is remaining normal which
  mean it's possible not to schedule alarm callback
  in-time if system is busy.

CRs-Fixed: 935097
Change-Id: I10dff46af800d55f0e816353a0f39cfe3150d22f

3 files changed, 30 insertions, 0 deletions

diff --git a/osi/include/thread.h b/osi/include/thread.h
index def4aa509..9e5602a41 100644
--- a/osi/include/thread.h
+++ b/osi/include/thread.h
@@ -23,6 +23,9 @@
 
 #define THREAD_NAME_MAX 16
 
+// Increase callback thread priority to high
+#define TIMER_CALLBACK_THREAD_PRIORITY -19
+
 typedef struct reactor_t reactor_t;
 typedef struct thread_t thread_t;
 typedef void (*thread_fn)(void *context);
@@ -58,6 +61,11 @@ bool thread_post(thread_t *thread, thread_fn func, void *context);
 // |thread| may not be NULL.
 void thread_stop(thread_t *thread);
 
+// Attempts to sets the |priority| of a given |thread|.
+// The |thread| has to be running for this call to succeed.
+// Returns true on success.
+bool thread_set_priority(thread_t *thread, int priority);
+
 // Returns true if the current thread is the same as the one represented by |thread|.
 // |thread| may not be NULL.
 bool thread_is_self(const thread_t *thread);
diff --git a/osi/src/alarm.c b/osi/src/alarm.c
index 761c6f315..ff168297c 100644
--- a/osi/src/alarm.c
+++ b/osi/src/alarm.c
@@ -35,6 +35,7 @@
 #include "osi/include/semaphore.h"
 #include "osi/include/thread.h"
 
+
 struct alarm_t {
   // The lock is held while the callback for this alarm is being executed.
   // It allows us to release the coarse-grained monitor lock while a potentially
@@ -241,6 +242,12 @@ static bool lazy_initialize(void) {
     return false;
   }
 
+  // boost timer thread to high for getting alarm callback with priority
+  // during a2dp music playback, media task/btu/hci/event threads are all high priority
+  // but actual callback thread is remaining normal which mean it's possible not to
+  // schedule alarm callback in-time if system is busy
+  thread_set_priority(callback_thread, TIMER_CALLBACK_THREAD_PRIORITY);
+
   thread_post(callback_thread, callback_dispatch, NULL);
   return true;
 }
diff --git a/osi/src/thread.c b/osi/src/thread.c
index d0824436e..9e4b6a4e4 100644
--- a/osi/src/thread.c
+++ b/osi/src/thread.c
@@ -24,6 +24,7 @@
 #include <pthread.h>
 #include <string.h>
 #include <sys/prctl.h>
+#include <sys/resource.h>
 #include <sys/types.h>
 
 #include "osi/include/allocator.h"
@@ -122,6 +123,20 @@ void thread_free(thread_t *thread) {
   osi_free(thread);
 }
 
+bool thread_set_priority(thread_t *thread, int priority) {
+  if (!thread)
+    return false;
+
+  const int rc = setpriority(PRIO_PROCESS, thread->tid, priority);
+  if (rc < 0) {
+    LOG_ERROR("%s unable to set thread priority %d for tid %d, error %d",
+      __func__, priority, thread->tid, rc);
+    return false;
+  }
+
+  return true;
+}
+
 void thread_join(thread_t *thread) {
   assert(thread != NULL);