Bug-fix: guarantee atomicity for FOP and GACC.

FOP, CAS and GACC are atomic "read-modify-write" operations,
which means when the target window is defined on a SHM region,
we need inter-process lock to guarantee the atomicity of the
entire "read+OP". The current implementation is correct for
SHM-based RMA operations, but not correct for AM-based RMA
operations: for SHM-based operations, it protects the entire
"read+OP", but for AM-based operations, it only protects the
"OP" part.

This patch fixes this issue by protecting the memory copy to
temporary buffer and computation together for AM-based operations.

Fix ticket 2226
Signed-off-by: Pavan Balaji <balaji@anl.gov>

src/mpid/ch3/src/ch3u_handle_recv_req.c

@@ -255,6 +255,9 @@ int MPIDI_CH3_ReqHandler_GaccumRecvComplete( MPIDI_VC_t *vc,
     MPIU_CHKPMEM_MALLOC(resp_req->dev.user_buf, void *, rreq->dev.user_count * type_size,
                         mpi_errno, "GACC resp. buffer");
 
+    if (win_ptr->shm_allocated == TRUE)
+        MPIDI_CH3I_SHM_MUTEX_LOCK(win_ptr);
+
     if (MPIR_DATATYPE_IS_PREDEFINED(rreq->dev.datatype)) {
         MPIU_Memcpy(resp_req->dev.user_buf, rreq->dev.real_user_buf,
                     rreq->dev.user_count * type_size);
@@ -268,6 +271,16 @@ int MPIDI_CH3_ReqHandler_GaccumRecvComplete( MPIDI_VC_t *vc,
         MPID_Segment_free(seg);
     }
 
+    /* accumulate data from tmp_buf into user_buf */
+    mpi_errno = do_accumulate_op(rreq->dev.final_user_buf, rreq->dev.real_user_buf,
+                                 rreq->dev.user_count, rreq->dev.datatype, rreq->dev.op);
+    if (mpi_errno) {
+        MPIU_ERR_POP(mpi_errno);
+    }
+
+    if (win_ptr->shm_allocated == TRUE)
+        MPIDI_CH3I_SHM_MUTEX_UNLOCK(win_ptr);
+
     resp_req->dev.OnFinal = MPIDI_CH3_ReqHandler_GaccumSendComplete;
     resp_req->dev.OnDataAvail = MPIDI_CH3_ReqHandler_GaccumSendComplete;
     resp_req->dev.target_win_handle = rreq->dev.target_win_handle;
@@ -322,17 +335,6 @@ int MPIDI_CH3_ReqHandler_GaccumRecvComplete( MPIDI_VC_t *vc,
 
     MPIU_Assert(MPIDI_Request_get_type(rreq) == MPIDI_REQUEST_TYPE_GET_ACCUM_RESP);
 
-    if (win_ptr->shm_allocated == TRUE)
-        MPIDI_CH3I_SHM_MUTEX_LOCK(win_ptr);
-    /* accumulate data from tmp_buf into user_buf */
-    mpi_errno = do_accumulate_op(rreq->dev.final_user_buf, rreq->dev.real_user_buf,
-                                 rreq->dev.user_count, rreq->dev.datatype, rreq->dev.op);
-    if (win_ptr->shm_allocated == TRUE)
-        MPIDI_CH3I_SHM_MUTEX_UNLOCK(win_ptr);
-    if (mpi_errno) {
-        MPIU_ERR_POP(mpi_errno);
-    }
-
     /* free the temporary buffer */
     MPIR_Type_get_true_extent_impl(rreq->dev.datatype, &true_lb, &true_extent);
     MPIU_Free((char *) rreq->dev.final_user_buf + true_lb);
@@ -1023,6 +1025,10 @@ static inline int perform_get_acc_in_lock_queue(MPID_Win *win_ptr, MPIDI_RMA_Loc
     MPID_Datatype_get_size_macro(get_accum_pkt->datatype, type_size);
     sreq->dev.user_buf = (void *)MPIU_Malloc(get_accum_pkt->count * type_size);
 
+    /* Perform ACCUMULATE OP */
+    if (win_ptr->shm_allocated == TRUE)
+        MPIDI_CH3I_SHM_MUTEX_LOCK(win_ptr);
+
     if (MPIR_DATATYPE_IS_PREDEFINED(get_accum_pkt->datatype)) {
         MPIU_Memcpy(sreq->dev.user_buf, get_accum_pkt->addr,
                     get_accum_pkt->count * type_size);
@@ -1037,6 +1043,21 @@ static inline int perform_get_acc_in_lock_queue(MPID_Win *win_ptr, MPIDI_RMA_Loc
         MPID_Segment_free(seg);
     }
 
+    if (lock_entry->data == NULL) {
+        /* All data fits in packet header */
+        mpi_errno = do_accumulate_op(get_accum_pkt->data, get_accum_pkt->addr,
+                                     get_accum_pkt->count, get_accum_pkt->datatype, get_accum_pkt->op);
+        if (mpi_errno != MPI_SUCCESS) MPIU_ERR_POP(mpi_errno);
+    }
+    else {
+        mpi_errno = do_accumulate_op(lock_entry->data, get_accum_pkt->addr,
+                                     get_accum_pkt->count, get_accum_pkt->datatype, get_accum_pkt->op);
+        if (mpi_errno != MPI_SUCCESS) MPIU_ERR_POP(mpi_errno);
+    }
+
+    if (win_ptr->shm_allocated == TRUE)
+        MPIDI_CH3I_SHM_MUTEX_UNLOCK(win_ptr);
+
     /* here we increment the Active Target counter to guarantee the GET-like
        operation are completed when counter reaches zero. */
     win_ptr->at_completion_counter++;
@@ -1096,25 +1117,6 @@ static inline int perform_get_acc_in_lock_queue(MPID_Win *win_ptr, MPIDI_RMA_Loc
 	MPIU_ERR_SETANDJUMP(mpi_errno, MPI_ERR_OTHER, "**ch3|rmamsg");
     }
 
-    /* Perform ACCUMULATE OP */
-    if (win_ptr->shm_allocated == TRUE)
-        MPIDI_CH3I_SHM_MUTEX_LOCK(win_ptr);
-
-    if (lock_entry->data == NULL) {
-        /* All data fits in packet header */
-        mpi_errno = do_accumulate_op(get_accum_pkt->data, get_accum_pkt->addr,
-                                     get_accum_pkt->count, get_accum_pkt->datatype, get_accum_pkt->op);
-        if (mpi_errno != MPI_SUCCESS) MPIU_ERR_POP(mpi_errno);
-    }
-    else {
-        mpi_errno = do_accumulate_op(lock_entry->data, get_accum_pkt->addr,
-                                     get_accum_pkt->count, get_accum_pkt->datatype, get_accum_pkt->op);
-        if (mpi_errno != MPI_SUCCESS) MPIU_ERR_POP(mpi_errno);
-    }
-
-    if (win_ptr->shm_allocated == TRUE)
-        MPIDI_CH3I_SHM_MUTEX_UNLOCK(win_ptr);
-
  fn_exit:
     return mpi_errno;
  fn_fail:
@@ -1149,6 +1151,9 @@ static inline int perform_fop_in_lock_queue(MPID_Win *win_ptr, MPIDI_RMA_Lock_en
         fop_resp_pkt->flags |= MPIDI_CH3_PKT_FLAG_RMA_FLUSH_ACK;
     fop_resp_pkt->immed_len = fop_pkt->immed_len;
 
+    if (win_ptr->shm_allocated == TRUE)
+        MPIDI_CH3I_SHM_MUTEX_LOCK(win_ptr);
+
     /* copy data to resp pkt header */
     void *src = fop_pkt->addr, *dest = fop_resp_pkt->data;
     mpi_errno = immed_copy(src, dest, (size_t)fop_resp_pkt->immed_len);
@@ -1158,12 +1163,11 @@ static inline int perform_fop_in_lock_queue(MPID_Win *win_ptr, MPIDI_RMA_Lock_en
     if (fop_pkt->op != MPI_NO_OP) {
         MPI_User_function *uop = MPIR_OP_HDL_TO_FN(fop_pkt->op);
         int one = 1;
-        if (win_ptr->shm_allocated == TRUE)
-            MPIDI_CH3I_SHM_MUTEX_LOCK(win_ptr);
         (*uop)(fop_pkt->data, fop_pkt->addr, &one, &(fop_pkt->datatype));
+    }
+
     if (win_ptr->shm_allocated == TRUE)
         MPIDI_CH3I_SHM_MUTEX_UNLOCK(win_ptr);
-    }
 
     /* send back the original data */
     MPIU_THREAD_CS_ENTER(CH3COMM,vc);

src/mpid/ch3/src/ch3u_rma_pkthandler.c

@@ -1098,6 +1098,9 @@ int MPIDI_CH3_PktHandler_FOP(MPIDI_VC_t * vc, MPIDI_CH3_Pkt_t * pkt,
         fop_resp_pkt->flags |= MPIDI_CH3_PKT_FLAG_RMA_FLUSH_ACK;
     fop_resp_pkt->immed_len = fop_pkt->immed_len;
 
+    if (win_ptr->shm_allocated == TRUE)
+        MPIDI_CH3I_SHM_MUTEX_LOCK(win_ptr);
+
     /* copy data to resp pkt header */
     void *src = fop_pkt->addr, *dest = fop_resp_pkt->data;
     mpi_errno = immed_copy(src, dest, (size_t)fop_resp_pkt->immed_len);
@@ -1107,12 +1110,11 @@ int MPIDI_CH3_PktHandler_FOP(MPIDI_VC_t * vc, MPIDI_CH3_Pkt_t * pkt,
     if (fop_pkt->op != MPI_NO_OP) {
         MPI_User_function *uop = MPIR_OP_HDL_TO_FN(fop_pkt->op);
         int one = 1;
-        if (win_ptr->shm_allocated == TRUE)
-            MPIDI_CH3I_SHM_MUTEX_LOCK(win_ptr);
         (*uop)(fop_pkt->data, fop_pkt->addr, &one, &(fop_pkt->datatype));
+    }
+
     if (win_ptr->shm_allocated == TRUE)
         MPIDI_CH3I_SHM_MUTEX_UNLOCK(win_ptr);
-    }
 
     /* send back the original data */
     MPIU_THREAD_CS_ENTER(CH3COMM,vc);