a bug in if_uba.c (not that serious)

[salkind%nyu at sri-unix.UUCP]

From:  Lou Salkind <salkind at nyu>

Subject: a bug in if_uba.c (not that serious)
Index:	sys/vaxif/if_uba. 4.2BSD

Description:
	There are two problems in if_uba.c:if_wubaput:
	(1) there is a superfluous instruction
	(2) the variable x is used for two different purposes in if_wubaput.
	This will cause transfers of two full clicks or more to fail.
	(Luckily the network interfaces don't do this currently.)
Repeat-By:
	Transfer 2K packets over your network device...
Fix:
	The diff follows.  Note all the routines assume hlen < PGSIZE
	(a very reasonable assumption, but it should be noted).

*** /tmp/,RCSt1008503	Tue Mar 13 18:30:59 1984
--- /tmp/,RCSt2008503	Tue Mar 13 18:31:00 1984
***************
*** 1,3
  /*	if_uba.c	6.1	83/07/29	*/
  
  #include "../machine/pte.h"

--- 1,7 -----
+ #ifdef	RCSIDENT
+ static char *rcsid = "$Header: /usr/sys/vaxif/RCS/if_uba.c,v 1.2 84/03/13 01:01:40 salkind Exp $";
+ #endif
+ 
  /*	if_uba.c	6.1	83/07/29	*/
  
  #include "../machine/pte.h"
***************
*** 31,36
   * with the header, and nmr more UNIBUS map registers for i/o on the adapter,
   * doing this twice: once for reading and once for writing.  We also
   * allocate page frames in the mbuffer pool for these pages.
   */
  if_ubainit(ifu, uban, hlen, nmr)
  	register struct ifuba *ifu;

--- 35,41 -----
   * with the header, and nmr more UNIBUS map registers for i/o on the adapter,
   * doing this twice: once for reading and once for writing.  We also
   * allocate page frames in the mbuffer pool for these pages.
+  * NOTE IT IS IMPLICTLY ASSUMED THAT hlen < PGSIZE.
   */
  if_ubainit(ifu, uban, hlen, nmr)
  	register struct ifuba *ifu;
***************
*** 198,204
  	register caddr_t cp, dp;
  	register int i;
  	int xswapd = 0;
! 	int x, cc;
  
  	cp = ifu->ifu_w.ifrw_addr;
  	while (m) {

--- 203,209 -----
  	register caddr_t cp, dp;
  	register int i;
  	int xswapd = 0;
! 	int x, cc, t;
  
  	cp = ifu->ifu_w.ifrw_addr;
  	while (m) {
***************
*** 234,240
  	cc = cp - ifu->ifu_w.ifrw_addr;
  	x = ((cc - ifu->ifu_hlen) + CLBYTES - 1) >> CLSHIFT;
  	ifu->ifu_xswapd &= ~xswapd;
- 	xswapd &= ~ifu->ifu_xswapd;
  	while (i = ffs(ifu->ifu_xswapd)) {
  		i--;
  		if (i >= x)

--- 239,244 -----
  	cc = cp - ifu->ifu_w.ifrw_addr;
  	x = ((cc - ifu->ifu_hlen) + CLBYTES - 1) >> CLSHIFT;
  	ifu->ifu_xswapd &= ~xswapd;
  	while (i = ffs(ifu->ifu_xswapd)) {
  		i--;
  		if (i >= x)
***************
*** 241,247
  			break;
  		ifu->ifu_xswapd &= ~(1<<i);
  		i *= CLSIZE;
! 		for (x = 0; x < CLSIZE; x++) {
  			ifu->ifu_w.ifrw_mr[i] = ifu->ifu_wmap[i];
  			i++;
  		}

--- 245,251 -----
  			break;
  		ifu->ifu_xswapd &= ~(1<<i);
  		i *= CLSIZE;
! 		for (t = 0; t < CLSIZE; t++) {
  			ifu->ifu_w.ifrw_mr[i] = ifu->ifu_wmap[i];
  			i++;
  		}