ib_srpt: Only complain if immediate data has to be copied if CONFIG_SLUB_DEBUG=n

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@7046 d57e44dd-8a1f-0410-8b47-8ef2f437770f

srpt/session-management.txt

@@ -8,7 +8,7 @@ The following actions related to SRP sessions can all occur concurrently:
 * HCA driver invokes the QP async event handler srpt_qp_event().
 * HCA transfers data between initiator and target via RDMA.
 * srpt_compl_thread() polls the QP.
-* SCST core invokes one of the callback functions defined in srpt_template().
+* SCST core invokes one of the callback functions defined in srpt_template.
 
 The actions that occur over the lifetime of a session are as follows:
 - A REQ message is received from the initiator.

srpt/src/ib_srpt.c

@@ -809,8 +809,12 @@ static struct srpt_ioctx *srpt_alloc_ioctx(struct srpt_device *sdev,
 	if (!ioctx->buf)
 		goto err_free_ioctx;
 
-	/* Complain if it is not safe to use zero-copy */
-	WARN_ON_ONCE(alignment_offset && ((uintptr_t)ioctx->buf & 511));
+	if (alignment_offset && ((uintptr_t)ioctx->buf & 511)) {
+		pr_warn("Disabling zero-copy for immediate data\n");
+#ifndef CONFIG_SLUB_DEBUG
+		WARN_ON_ONCE(true);
+#endif
+	}
 
 	ioctx->dma = ib_dma_map_single(sdev->device, ioctx->buf,
 				       dma_size + alignment_offset, dir);
@@ -3541,6 +3545,10 @@ static int srpt_xfer_data(struct srpt_rdma_ch *ch,
 			unsigned offset = 0, len;
 			uint8_t *buf;
 
+			/*
+			 * Copy the immediate data if srpt_get_desc_tbl()
+			 * did not call sg_init_one().
+			 */
 			len = scst_get_buf_first(cmd, &buf);
 			while (len > 0) {
 				memcpy(buf, ioctx->imm_data + offset, len);