netdev - Re: [PATCH net v3 0/4] net-sysfs: fix race conditions in the xps code

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Date:   Wed, 23 Dec 2020 15:26:08 -0800
From:   Alexander Duyck <alexander.duyck@...il.com>
To:     Antoine Tenart <atenart@...nel.org>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Netdev <netdev@...r.kernel.org>, Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH net v3 0/4] net-sysfs: fix race conditions in the xps code

On Wed, Dec 23, 2020 at 1:23 PM Antoine Tenart <atenart@...nel.org> wrote:
>
> Hello all,
>
> This series fixes race conditions in the xps code, where out of bound
> accesses can occur when dev->num_tc is updated, triggering oops. The
> root cause is linked to locking issues. An explanation is given in each
> of the commit logs.
>
> We had a discussion on the v1 of this series about using the xps_map
> mutex instead of the rtnl lock. While that seemed a better compromise,
> v2 showed the added complexity wasn't best for fixes. So we decided to
> go back to v1 and use the rtnl lock.
>
> Because of this, the only differences between v1 and v3 are improvements
> in the commit messages.
>
> Thanks!
> Antoine
>
> Antoine Tenart (4):
>   net-sysfs: take the rtnl lock when storing xps_cpus
>   net-sysfs: take the rtnl lock when accessing xps_cpus_map and num_tc
>   net-sysfs: take the rtnl lock when storing xps_rxqs
>   net-sysfs: take the rtnl lock when accessing xps_rxqs_map and num_tc
>
>  net/core/net-sysfs.c | 65 ++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 53 insertions(+), 12 deletions(-)
>

The series looks fine to me. Not the prettiest in the case of showing
the maps, but I don't think much can be done about that since we have
to return an error type and release the rtnl_lock.

Reviewed-by: Alexander Duyck <alexanderduyck@...com>