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Date:      Wed, 19 Nov 2014 09:03:12 +0000 (UTC)
From:      Hans Petter Selasky <hselasky@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org
Subject:   svn commit: r274704 - in stable/10/sys: net netinet
Message-ID:  <201411190903.sAJ93C0b004564@svn.freebsd.org>
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Author: hselasky
Date: Wed Nov 19 09:03:12 2014
New Revision: 274704
URL: https://svnweb.freebsd.org/changeset/base/274704

Log:
  MFC r274376:
  Fix some minor TSO issues:
  - Improve description of TSO limits.
  - Remove a not needed KASSERT()
  - Remove some not needed variable casts.
  
  Sponsored by:	Mellanox Technologies

Modified:
  stable/10/sys/net/if.c
  stable/10/sys/net/if_var.h
  stable/10/sys/netinet/tcp_output.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/net/if.c
==============================================================================
--- stable/10/sys/net/if.c	Wed Nov 19 08:59:49 2014	(r274703)
+++ stable/10/sys/net/if.c	Wed Nov 19 09:03:12 2014	(r274704)
@@ -731,13 +731,6 @@ if_attach_internal(struct ifnet *ifp, in
 				    ifp->if_hw_tsomaxsegsize);
 			}
 		}
-		/*
-		 * If the "if_hw_tsomax" limit is set, check if it is
-		 * too small:
-		 */
-		KASSERT(ifp->if_hw_tsomax == 0 ||
-		    ifp->if_hw_tsomax >= (IP_MAXPACKET / 8),
-		    ("%s: if_hw_tsomax is outside of range", __func__));
 #endif
 	}
 #ifdef VIMAGE

Modified: stable/10/sys/net/if_var.h
==============================================================================
--- stable/10/sys/net/if_var.h	Wed Nov 19 08:59:49 2014	(r274703)
+++ stable/10/sys/net/if_var.h	Wed Nov 19 09:03:12 2014	(r274704)
@@ -210,11 +210,23 @@ struct ifnet {
 	u_int	if_fib;			/* interface FIB */
 	u_char	if_alloctype;		/* if_type at time of allocation */
 
-	u_int	if_hw_tsomax;		/* TSO total burst length
-					 * limit in bytes. A value of
-					 * zero means no limit. Have
-					 * to find a better place for
-					 * it eventually. */
+	/*
+	 * Network adapter TSO limits:
+	 * ===========================
+	 *
+	 * If the "if_hw_tsomax" field is zero the maximum segment
+	 * length limit does not apply. If the "if_hw_tsomaxsegcount"
+	 * or the "if_hw_tsomaxsegsize" field is zero the TSO segment
+	 * count limit does not apply. If all three fields are zero,
+	 * there is no TSO limit.
+	 *
+	 * NOTE: The TSO limits only apply to the data payload part of
+	 * a TCP/IP packet. That means there is no need to subtract
+	 * space for ethernet-, vlan-, IP- or TCP- headers from the
+	 * TSO limits unless the hardware driver in question requires
+	 * so.
+	 */
+	u_int	if_hw_tsomax;
 
 	/*
 	 * Spare fields are added so that we can modify sensitive data

Modified: stable/10/sys/netinet/tcp_output.c
==============================================================================
--- stable/10/sys/netinet/tcp_output.c	Wed Nov 19 08:59:49 2014	(r274703)
+++ stable/10/sys/netinet/tcp_output.c	Wed Nov 19 09:03:12 2014	(r274704)
@@ -803,9 +803,9 @@ send:
 				max_len = (if_hw_tsomax - hdrlen);
 				if (max_len <= 0) {
 					len = 0;
-				} else if (len > (u_int)max_len) {
+				} else if (len > max_len) {
 					sendalot = 1;
-					len = (u_int)max_len;
+					len = max_len;
 				}
 			}
 
@@ -818,7 +818,7 @@ send:
 				max_len = 0;
 				mb = sbsndmbuf(&so->so_snd, off, &moff);
 
-				while (mb != NULL && (u_int)max_len < len) {
+				while (mb != NULL && max_len < len) {
 					u_int mlen;
 					u_int frags;
 
@@ -852,9 +852,9 @@ send:
 				}
 				if (max_len <= 0) {
 					len = 0;
-				} else if (len > (u_int)max_len) {
+				} else if (len > max_len) {
 					sendalot = 1;
-					len = (u_int)max_len;
+					len = max_len;
 				}
 			}
 
@@ -865,7 +865,7 @@ send:
 			 */
 			max_len = (tp->t_maxopd - optlen);
 			if ((off + len) < so->so_snd.sb_cc) {
-				moff = len % (u_int)max_len;
+				moff = len % max_len;
 				if (moff != 0) {
 					len -= moff;
 					sendalot = 1;
@@ -876,8 +876,8 @@ send:
 			 * In case there are too many small fragments
 			 * don't use TSO:
 			 */
-			if (len <= (u_int)max_len) {
-				len = (u_int)max_len;
+			if (len <= max_len) {
+				len = max_len;
 				sendalot = 1;
 				tso = 0;
 			}

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