netdev - Re: 3.10.0-rc2 mlx4 not receiving packets for some multicast groups

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Date:	Thu, 30 May 2013 23:42:22 +0300
From:	Or Gerlitz <or.gerlitz@...il.com>
To:	Shawn Bohrer <shawn.bohrer@...il.com>,
	Vlad Yasevich <vyasevic@...hat.com>
Cc:	netdev@...r.kernel.org, Hadar Hen Zion <hadarh@...lanox.com>,
	Amir Vadai <amirv@...lanox.com>, Jiri Pirko <jiri@...nulli.us>
Subject: Re: 3.10.0-rc2 mlx4 not receiving packets for some multicast groups

On Thu, May 30, 2013 at 11:31 PM, Shawn Bohrer <shawn.bohrer@...il.com> wrote:
>> So we need to
>> debug/bisect why without the patch (what you call high_rate_steer=0)
>> you don't get data on all groups. Can you bisect that on a single
>> node, e.g set the rest of the environment with 3.4 that works, and on
>> a given node see what is the commit that breaks that?

> Done. It appears that the patch that breaks receiving packets on many
> different multicast groups/sockets is:
>
> commit 4cd729b04285b7330edaf5a7080aa795d6d15ff3
> Author: Vlad Yasevich <vyasevic@...hat.com>
> Date:   Mon Apr 15 09:54:25 2013 +0000
>
>     net: add dev_uc_sync_multiple() and dev_mc_sync_multiple() api
>
>     The current implementation of dev_uc_sync/unsync() assumes that there is
>     a strict 1-to-1 relationship between the source and destination of the sync.
>     In other words, once an address has been synced to a destination device, it
>     will not be synced to any other device through the sync API.
>     However, there are some virtual devices that aggreate a number of lower
>     devices and need to sync addresses to all of them.  The current
>     API falls short there.
>
>     This patch introduces a new dev_uc_sync_multiple() api that can be called
>     in the above circumstances and allows sync to work for every invocation.
>
>     CC: Jiri Pirko <jiri@...nulli.us>
>     Signed-off-by: Vlad Yasevich <vyasevic@...hat.com>
>     Signed-off-by: David S. Miller <davem@...emloft.net>
>
> I've confirmed that reverting this patch on top of 3.10-rc3 allows me
> to receive packets on all of my multicast groups without the Mellanox
> high_rate_steer option set.

OK, impressive debugging... so what do we do from here? Vlad, Shawn
observes a regression once this patch is used on a large scale setup
that uses many multicast groups (you can read the posts done earlier
on this thread), does this rings any bell w.r.t to the actual problem
in the patch?

Or.
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