RxRPC: 3 issues found in my example code

[Leon Liu]

Hi Tim,

Thank you so much for your very quick response and patch!

I've tried the patch. It did fixed the issue #1. I know it maybe a temporary
fixing, whatever, I observed two new issues:

1. The fixing increases probability of hitting issue #2 (rxrpc stack return
"local error 103, rx busy") dramatically. Probability changes from 1/100000
to 1/5000. You have to turn rxrpc log off to reproduce the issue.
Occasionally, this can be fixed by re-insmod af-rxrpc.ko at sender.
2. After hitting issue #2 a lot of times, receiver kernel hangs. This was
reproduced 3 times. 

I can run the test again if you have a formal fixing to see if I can still
reproduce these two additional issues.

Thanks!
Leon

-----Original Message-----
From: Tim Smith [mailto:tim at electronghost.co.uk] 
Sent: Saturday, April 26, 2014 11:15 PM
To: linux-afs at lists.infradead.org
Cc: Leon Liu; dhowells at redhat.com
Subject: Re: RxRPC: 3 issues found in my example code

On Friday 25 April 2014 19:10:13 Tim Smith wrote:
> On Friday 25 April 2014 09:51:35 Leon Liu wrote:
> > ====================================
> > Issues 1:
> > ====================================
> > when I send out a call data larger than 1500(aka: MTU size), the 
> > first data snippet was received by receiver successfully but failed 
> > for following snippets. No problem if call data is less than MTU 
> > size.
> 
> This is almost certainly my fault. I suspect removing the spinlocks 
> has introduced a race.
> 
> I will take a look at this over the weekend.

I've reproduced something very similar to your first report, and the
attached hack fixes it locally for me. If it fixes it for you, I will make
something less ugly. 

--
Tim Smith <tim at electronghost.co.uk>
England Prevails

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