netdev - Re: [PATCH net] ipv4: disable BH in set_ping_group

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Date:   Thu, 20 Oct 2016 13:43:29 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, Eric Salo <salo@...gle.com>
Subject: Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

On Thu, 2016-10-20 at 12:44 -0700, Cong Wang wrote:
> On Thu, Oct 20, 2016 at 12:40 PM, Cong Wang <xiyou.wangcong@...il.com> wrote:
> > On Thu, Oct 20, 2016 at 12:32 PM, Cong Wang <xiyou.wangcong@...il.com> wrote:
> >> On Thu, Oct 20, 2016 at 10:26 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> >>> From: Eric Dumazet <edumazet@...gle.com>
> >>>
> >>> In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
> >>> range") Cong added BH protection in set_local_port_range() but missed
> >>> that same fix was needed in set_ping_group_range()
> >>
> >> Don't know why ping_group_range shares the same lock with local_port_range...
> >> Perhaps just for saving a few bytes, but that is why I missed this place.
> >
> > Hold on... We clearly have typos there... Your fix is not correct.
> 
> We need the attached patch, your patch should be reverted, because
> unlike local_port_range we never read it in BH context, no need to bother _bh.

Well, we do not change this sysctl very often, so I am not sure why we
need different seqlocks to protect these ranges.

Seems a waste of space really (per netns)