Race condition clearing bit vectors that are already clear in Init.init.

[tinyos-2.x.git] / tos / system / SharedArbiterP.nc

diff --git a/tos/system/SharedArbiterP.nc b/tos/system/SharedArbiterP.nc
index c3503131cde02a93edb6d775de6a5b9d807ad0d6..40afb970ed91b670578ba4091ac385d323eb3115 100644 (file)
--- a/tos/system/SharedArbiterP.nc
+++ b/tos/system/SharedArbiterP.nc
@@ -33,14 +33,11 @@
  * switched subsystem.  For example, a communications bus that can handle IO
  * for multiple clients simultaneously, but is powered down when not in use.
  *
- * p_dfltOwnerId = uniqueCount() use by the resource.  see SharedArbiterC
- *
  * @author R. Steve McKown <rsmckown@gmail.com>
  */
 
-generic module SharedArbiterP(uint8_t p_dfltOwnerId) {
+generic module SharedArbiterP() {
   provides {
-    interface Init;
     interface Resource[uint8_t id];
     interface ResourceDefaultOwner;
     interface ArbiterInfo;
@@ -119,17 +116,14 @@ implementation {
     }
   }
 
-  command error_t Init.init()
-  {
-    call GrantedVector.clearAll();
-    call RequestingVector.clearAll();
-    return SUCCESS;
-  }
-
   async command error_t Resource.request[uint8_t id]()
   {
+    /* The Resource docs do not say what happens when a user calls
+     * Resource.request() after the resource has already been granted.  We
+     * elect to call EBUSY, as if the request was still in process.
+     */
     if (call RequestingVector.get(id) || call GrantedVector.get(id))
-      return FAIL;
+      return EBUSY;
 
     addRequesting(id);
     if (call State.isIdle())
@@ -141,8 +135,12 @@ implementation {
 
   async command error_t Resource.immediateRequest[uint8_t id]()
   {
+    /* The Resource docs do not say what happens when a user calls
+     * Resource.request() after the resource has already been granted.  We
+     * elect to call EBUSY, as if the request was still in process.
+     */
     if (call RequestingVector.get(id) || call GrantedVector.get(id))
-      return FAIL;
+      return EBUSY;
 
     if (call State.isIdle())
       signal ResourceDefaultOwner.immediateRequested();
@@ -167,14 +165,11 @@ implementation {
 
   async command error_t ResourceDefaultOwner.release()
   {
-    atomic {
-      if (m_requesting > 0) {
-       call State.forceState(S_GRANTED);
-       post grantedTask();
-       return SUCCESS;
-      } else
-       return FAIL;
-    }
+    if (call State.requestState(S_GRANTED) == SUCCESS) {
+      post grantedTask();
+      return SUCCESS;
+    } else
+      return FAIL;
   }
 
   async command bool ArbiterInfo.inUse()