Messages in this thread | | | Date | Fri, 27 Sep 2013 07:47:12 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 4/4] [RFC] ipv6: Fix for possible ipv6 seqlock deadlock |
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* John Stultz <john.stultz@linaro.org> wrote:
> On 09/26/2013 12:30 PM, Eric Dumazet wrote: > > On Thu, 2013-09-26 at 11:34 -0700, John Stultz wrote: > >> While enabling lockdep on seqlocks, I ran accross the warning below > >> caused by the ipv6 stats being updated in both irq and non-irq context. > >> > >> This is a novice attempt to correct the issue, and with this patch > >> the warning goes away. Any better solutions would be appreciated! > > ... > > > >> > >> out_err_release: > >> - if (err == -ENETUNREACH) > >> + if (err == -ENETUNREACH) { > >> + unsigned long flags; > >> + /* some of the stats are locked in irq context */ > >> + local_irq_save(flags); > >> IP6_INC_STATS_BH(net, NULL, IPSTATS_MIB_OUTNOROUTES); > >> + local_irq_restore(flags); > >> + } > >> dst_release(*dst); > >> *dst = NULL; > >> return err; > > You better change IP6_INC_STATS_BH() to IP6_INC_STATS() > > > > On x86 for example, no extra code will be generated (no need to disable > > hard or soft irqs) > > Ah, thanks! Verified it resolves the warning as well, so I've changed my > patch to use your suggestion.
Btw., is this a deadlock that could occur upstream? If yes then adding a Cc: <stable@kernel.org> tag might be warranted.
Thanks,
Ingo
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