[svn-r5051] Fix for ticket #197, uninitialized usage of rreq->dev.recv_pending_count.

This ticket also converts the MPIDI_Request_recv_pending macro into two
macros which have slightly clearer names and usages.  The side effect of
the old macro was very confusing.

Reviewed by buntinas@.

src/mpid/ch3/include/mpidimpl.h

@@ -447,11 +447,17 @@ extern MPIDI_Process_t MPIDI_Process;
     (req_)->dev.cancel_pending = TRUE;			\
 }
 
-/* FIXME: Why does this have a side effect? */
-#define MPIDI_Request_recv_pending(req_, recv_pending_)	\
-    {								\
- 	*(recv_pending_) = --(req_)->dev.recv_pending_count;	\
-    }
+/* the following two macros were formerly a single confusing macro with side
+   effects named MPIDI_Request_recv_pending() */
+#define MPIDI_Request_check_pending(req_, recv_pending_)   \
+    do {                                                   \
+        *(recv_pending_) = (req_)->dev.recv_pending_count; \
+    } while (0)
+
+#define MPIDI_Request_decr_pending(req_)    \
+    do {                                    \
+        --(req_)->dev.recv_pending_count;   \
+    } while (0)
 
 /* MPIDI_Request_fetch_and_clear_rts_sreq() - atomically fetch current 
    partner RTS sreq and nullify partner request */

src/mpid/ch3/include/mpidpre.h

@@ -244,6 +244,8 @@ typedef struct MPIDI_Request {
 
     unsigned int   state;
     int            cancel_pending;
+    /* FIXME the precise meaning of this field is unclear, comments/docs
+       about it should be added */
     int            recv_pending_count;
 
     /* The next 8 are for RMA */

src/mpid/ch3/src/ch3u_handle_recv_req.c

@@ -436,7 +436,8 @@ int MPIDI_CH3_ReqHandler_UnpackUEBufComplete( MPIDI_VC_t *vc ATTRIBUTE((unused))
     
     MPIDI_FUNC_ENTER(MPID_STATE_MPIDI_CH3_REQHANDLER_UNPACKUEBUFCOMPLETE);
     
-    MPIDI_Request_recv_pending(rreq, &recv_pending);
+    MPIDI_Request_decr_pending(rreq);
+    MPIDI_Request_check_pending(rreq, &recv_pending);
     if (!recv_pending)
     { 
 	if (rreq->dev.recv_data_sz > 0)

src/mpid/ch3/src/ch3u_recvq.c

@@ -509,6 +509,7 @@ MPID_Request * MPIDI_CH3U_Recvq_FDP_or_AEU(MPIDI_Message_match * match,
 	int mpi_errno=0;
 	MPIDI_Request_create_rreq( rreq, mpi_errno, 
 				   found=FALSE;goto lock_exit );
+        rreq->dev.recv_pending_count = 1;
 	rreq->dev.match	= *match;
 	rreq->dev.next	= NULL;
 	if (recvq_unexpected_tail != NULL) {

src/mpid/ch3/src/mpid_irecv.c

@@ -79,7 +79,10 @@ int MPID_Irecv(void * buf, int count, MPI_Datatype datatype, int rank, int tag,
 		if (mpi_errno) MPIU_ERR_POP(mpi_errno);
 	    }
 
-            MPIDI_Request_recv_pending(rreq, &recv_pending);
+            /* the request was found in the unexpected queue, so it has a
+               recv_pending_count of at least 1 */
+            MPIDI_Request_decr_pending(rreq);
+            MPIDI_Request_check_pending(rreq, &recv_pending);
 	    if (!recv_pending)
 	    {
 		/* All of the data has arrived, we need to copy the data and 

src/mpid/ch3/src/mpid_recv.c

@@ -72,7 +72,10 @@ int MPID_Recv(void * buf, int count, MPI_Datatype datatype, int rank, int tag,
 		if (mpi_errno) MPIU_ERR_POP(mpi_errno);
 	    }
 	    
-            MPIDI_Request_recv_pending(rreq, &recv_pending);
+            /* the request was found in the unexpected queue, so it has a
+               recv_pending_count of at least 1 */
+            MPIDI_Request_decr_pending(rreq);
+            MPIDI_Request_check_pending(rreq, &recv_pending);
 	    if (!recv_pending)
 	    {
 		/* All of the data has arrived, we need to unpack the data and