Re: [tipc-discussion] Status of broadcast link-related patches

[Stephens, A. <all...@wi...>]

FYI, I've now pushed the patch for item 2) in the email below into the
TIPC 1.7 code stream. I'll get to the remaining items as soon as I can.
 
Regards,
Al


________________________________

	From: Stephens, Allan 
	Sent: Friday, August 27, 2010 1:54 PM
	To: 'Andrew Booth'
	Cc: tip...@li...
	Subject: RE: Status of broadcast link-related patches
	
	
	Hi Andrew:
	 
	This is a bit complicated, so I'm going to discuss this subject
in numbered parts.
	 
	1) So far, there has only been one broadcast link-related patch
accepted into TIPC 1.7 that isn't already in TIPC 1.7.7-rc1. You can
find it at the Ericsson TIPC repository using:
	 
	
http://tipc.cslab.ericsson.net/cgi-bin/gitweb.cgi?p=people/allan/tipc.gi
t;a=shortlog;h=tipc1.7
	 
	it's the patch labelled "Prevent broadcast link stalling in dual
LAN environments". I think this is the one commonly referred to as "Al's
patch", although you'll note that Laser also contributed to the
solution.
	 
	2) I've previously mentioned a second broadcast link fix that
looks good to me, namely the one that swaps the lines:
	 
	            tipc_bclink_acknowledge(n_ptr,
mod(n_ptr->bclink.acked + 10000));
	            tipc_bclink_remove_node(n_ptr->elm.addr);
	 
	in node_lost_contact(). Unless someone objects I'm planning on
submitting into TIPC 1.7 once I get a few minutes of spare time. This
patch was developed as the result of an anonymous posting to the TIPC
bug tracker.
	 
	3) I've got a patch from Surya from July 2009 which I think is
the one referred to as "Surya's patch". This patch was partly
incorporated into TIPC 1.7.7-rc1; you'll find it in the Ericsson
repository (same as above) dated March 25, 2010 under the label "Enhance
cleanup of broadcast link when contact with node is lost". I haven't yet
incorporated the rest of the patch as I haven't been able to determine
whether the other parts are really correct and/or essential. If you want
to try them out, the other parts are:
	 
	a) Change BCLINK_WIN_DEFAULT from 20 to 50.
	 
	b) In node_abort_link_changeover() replace:
	            l_ptr->reset_checkpoint = l_ptr->next_in_no;
	   with:
	           l_ptr->reset_checkpoint = 1;
	 
	I'm a bit suspicous of item a) since it seems like a change that
is more likely to be masking a problem than actually solving it; however
it's probably relatively harmless, and if it makes your current problems
go away then you might want to use it. I'm also suspicous about b)
because I think the correct solution is to set reset_checkpoint to an
invalid sequence number (eg. 0x10000) and check for this case in
link_recv_changeover_msg(), rather than setting the field to a
potentially legitimate sequence number (i.e. 1). Use at your own risk
for the time being ...
	 
	4) I haven't had a chance to look at Ying Xue's emails yet, so I
can't comment on them.
	 
	5) Likewise, I haven't had a chance to look at Laser's work
relating to the initialization of a link's peer session, which is what I
think Jon meant when he referred to "Laser's patch". Check out the TIPC
mailing list archive for Jon's post of June 18th on this subject. Jon
seems to think the work is correct so it'll probably be incorporated
into TIPC 1.7 once I get some time.
	 
	Hope this info helps.
	 
	Regards,
	Al
	 
	 


________________________________

		From: Andrew Booth [mailto:ab...@pt...] 
		Sent: Friday, August 27, 2010 10:37 AM
		To: Stephens, Allan
		Cc: tip...@li...
		Subject: 
		
		
		Hi Allan,
		
		We're now running TIPC 1.7.7rc1 and I'd like to apply
the patches relevant to trouble with name table distribution and
broadcast links getting stuck.
		
		I'm a little unclear as to what those patches are.
They've been referred to informally as Allan's patch, Surya's patch and
Laser's patch, but I'm not sure where to find the final versions.
		
		There's also a patch referenced here that seems to
handle a different broadcast link problem:
		
		    Aug 17, 2010 from Ying Xue  Re: [tipc-discussion]
Another possible fix for broadcast link woes? 
		    Aug 17, 2010 from Ying Xue  [tipc-discussion]
[PATCH] tipc: Fix bclink outqueue is released completely when a node is
lost
		
		Any help would be appreciated.
		
		Thanks,
		Andrew