hwcomposer: delay starting the uevent thread

- There is a race condition window between initializing hwcomposer as a
  whole and registering callback functions for when the uevents arrive. We
  can fix this issue by delaying the uevent thread kick off until the
  callback functions are registered.
- Add thread name to uevent thread

Change-Id: I30e23b411b92b6578f186b641f562462a8f23179

libhwcomposer/hwc.cpp

@@ -70,6 +70,9 @@ static void hwc_registerProcs(struct hwc_composer_device* dev,
         return;
     }
     ctx->device.reserved_proc[0] = (void*)procs;
+
+    // Now that we have the functions needed, kick off the uevent thread
+    init_uevent_thread(ctx);
 }
 
 static int hwc_prepare(hwc_composer_device_t *dev, hwc_layer_list_t* list)

libhwcomposer/hwc_uevents.cpp

@@ -23,6 +23,7 @@
 #include <hardware_legacy/uevent.h>
 #include <utils/Log.h>
 #include <sys/resource.h>
+#include <sys/prctl.h>
 #include <string.h>
 #include <stdlib.h>
 #include "hwc_utils.h"
@@ -88,6 +89,8 @@ static void *uevent_loop(void *param)
     memset(udata, 0, sizeof(udata));
     hwc_context_t * ctx = reinterpret_cast<hwc_context_t *>(param);
 
+    char thread_name[64] = "hwcUeventThread";
+    prctl(PR_SET_NAME, (unsigned long) &thread_name, 0, 0, 0);
     setpriority(PRIO_PROCESS, 0, HAL_PRIORITY_URGENT_DISPLAY);
     uevent_init();
 
@@ -102,6 +105,7 @@ static void *uevent_loop(void *param)
 void init_uevent_thread(hwc_context_t* ctx)
 {
     pthread_t uevent_thread;
+    ALOGI("Initializing UEvent Listener Thread");
     pthread_create(&uevent_thread, NULL, uevent_loop, (void*) ctx);
 }
 

libhwcomposer/hwc_utils.cpp

@@ -54,8 +54,6 @@ void initContext(hwc_context_t *ctx)
     ctx->mExtDisplay = new ExternalDisplay(ctx);
     MDPComp::init(ctx);
 
-    init_uevent_thread(ctx);
-
     char value[PROPERTY_VALUE_MAX];
     property_get("debug.egl.swapinterval", value, "1");
     ctx->swapInterval = atoi(value);