Messages in this thread | | | Date | Fri, 27 Sep 2013 09:00:27 -0700 | From | John Stultz <> | Subject | Re: [PATCH 4/4] [RFC] ipv6: Fix for possible ipv6 seqlock deadlock |
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On 09/26/2013 10:47 PM, Ingo Molnar wrote: > * 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.
It seems as such, so I'll add stable on my next submission.
thanks -john
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