svn commit: r260083 - head/sys/dev/iscsi

[Edward Tomasz Napierala]

Author: trasz
Date: Mon Dec 30 12:18:06 2013
New Revision: 260083
URL: http://svnweb.freebsd.org/changeset/base/260083

Log:
  Fix extremely slow operation with data digests enabled.  This was caused
  by receive code waiting for data digest even when the data segment was
  empty.  It didn't actually read it, but it waited until those four bytes
  become available in the socket buffer, i.e. until any other PDU (such as NOP)
  came in.
  
  PR:		kern/185240
  MFC after:	2 weeks
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sys/dev/iscsi/icl.c

Modified: head/sys/dev/iscsi/icl.c
==============================================================================
--- head/sys/dev/iscsi/icl.c	Mon Dec 30 09:04:06 2013	(r260082)
+++ head/sys/dev/iscsi/icl.c	Mon Dec 30 12:18:06 2013	(r260083)
@@ -239,7 +239,7 @@ icl_pdu_size(const struct icl_pdu *respo
 	    icl_pdu_padding(response);
 	if (response->ip_conn->ic_header_crc32c)
 		len += ISCSI_HEADER_DIGEST_SIZE;
-	if (response->ip_conn->ic_data_crc32c)
+	if (response->ip_data_len != 0 && response->ip_conn->ic_data_crc32c)
 		len += ISCSI_DATA_DIGEST_SIZE;
 
 	return (len);
@@ -615,7 +615,7 @@ icl_conn_receive_pdu(struct icl_conn *ic
 			break;
 
 		ic->ic_receive_state = ICL_CONN_STATE_DATA_DIGEST;
-		if (ic->ic_data_crc32c == false)
+		if (request->ip_data_len == 0 || ic->ic_data_crc32c == false)
 			ic->ic_receive_len = 0;
 		else
 			ic->ic_receive_len = ISCSI_DATA_DIGEST_SIZE;