[Ucip-devel] BUG found in nTrimQ in netbuf.c

[Mads C. <MC...@vo...>]

Hi everyone!

Please read this Robert.

And some days of seeking i finally found and annoying bug.
It seems that sometimes the transmit queue in the stacks gets corrupted.

I located the error in the nTrimQ function in netbuf.c.
Actually I'm not sure if any of you guys ever will see this error since =
I'm running the stack in a single task.

I would very much like you Robert to update the CVS, since my pc is not =
configured for the CVS anymore.

The error will sometimes occur when nTrim is called from nTrimQ. Read the =
comments in the source below.


Best wishes to you all,

Mads Christiansen
Partner Voxtream
www.voxtream.com=20


Here is the new nTrimQ function.


/*
 * nTrimQ - Trim bytes from the front of a buffer queue.
 * Note: The queue needs to be protected from collisions for the duration
 * of this call.
 * Return the number of bytes trimmed.
 */
int nTrimQ(char *dst, NBufQHdr *qh, u_int len)
{
	int st =3D 0;
=09
	if (qh && qh->qHead && len) {
		NBuf *n0;
		int trimmed;
	=09
		/* Trim entire chains. */
		while (qh->qHead && len >=3D qh->qHead->chainLen) {

			if ((qh->qHead =3D (n0 =3D qh->qHead)->nextChain) =
=3D=3D NULL)
				qh->qTail =3D NULL;
			qh->qLen--;
		=09
			n0->nextChain =3D NULL;

      if (dst)
      {
			  trimmed =3D nTrim(dst, &n0, len);
			  if (dst)
				  dst +=3D trimmed;
			  len -=3D trimmed;
			  st +=3D trimmed;
      }
      else
      {
        len -=3D n0->chainLen;
        st +=3D n0->chainLen;
      }
      if (n0) nFreeChain(n0);
		}
	=09
		/* If more to go, trim from next chain. */
		if (len && qh->qHead) {
			/*=20
			 * XXX LONG CRITICAL SECTION!!!  Could we pop this =
off the queue,
			 * trim it, and then replace the remainder?  Do we =
need a semaphore?=20
			 */
      trimmed =3D nTrim(dst, &qh->qHead, len);
			st +=3D trimmed;

      // Update tail pointer!!! SERIOUS BUGFIX /ma...@mo... 2002.01.11
      if (qh->qLen =3D=3D 1)
      {
        // nTrim might return a new nBuf in qh->qHead
        // IF qLen =3D=3D 1 we have to update qTrail!!!=20
        qh->qTail =3D qh->qHead;
      }
		}
	}
=09
	return st;
}