Re: [PATCH] IPoIB: fix faulty list maintenance in path and neigh list

[Pradeep Satyanarayana <pradeeps-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

On 02/17/2011 03:34 PM, Mike Marciniszyn wrote:
> We too have had installability, perhaps associated with these lists, but it has been difficult to diagnose.
>
> We duplicate it by forcing dropped packets and seeing the QP's come/go at the rate of 1000s a second because of the 0 rnr_retry and retry counts.  This analysis is in line behind other bug investigations.
>
> The list patch was a result of code inspection.
>
> Ralph's patch predates me.   His appears to move some list inserts to before a post, I'm assuming since an intervening completion could occur, but I haven't studied it in detail to see if any locking prevents it.
>
> I would be interested in Pradeep's test (OS, Hardware, scripts...)

As described in one of my previous mails (in the url given below):

The test is basically to run netperf in a loop from several client 
machines to a server. The server is unloading and reloading the modules 
(basically do an "openibd restart") at random times. The crashes 
recreate in several hours. I used some of the large IBM servers. They 
did not seem to recreate on say smaller blades.

>
> Mike
>
> -----Original Message-----
> From: roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org [mailto:roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org] On Behalf Of Roland Dreier
> Sent: Thursday, February 17, 2011 6:24 PM
> To: Pradeep Satyanarayana
> Cc: Mike Marciniszyn; linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Gary Leshner; Tom Elken
> Subject: Re: [PATCH] IPoIB: fix faulty list maintenance in path and neigh list
>
>> Yes, that is the crux of the issue. I had missed that ipoib_mcast_free() is
>> only called on remove_list.
>
> So do we have any idea of what this patch is fixing?  Any thoughts from
> the qlogic people involved in this patch?
>
>> While we are discussing IPoIB issues, how about the two other issues that
>> I illustrated previously. One was Ralph Campbell's patch for fixes to
>> ipoib_cm_start_rx_drain() and my questions wrt ipoib_neigh_cleanup()?
>
> I do need to take a good look at Ralph's patches to try and understand them
> and I hope apply them.  Not sure I still have any link to your questions though.

Here is the link to the detailed mail I sent:
http://www.spinics.net/lists/linux-rdma/msg07352.html

Thanks
Pradeep
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