netdev - Re: [PATCH] net: optimize cmpxchg in ip_idents

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Message-ID: <45224c36-9941-aae5-aca4-e2c8e3723355@gmail.com>
Date:   Fri, 17 Jan 2020 10:48:19 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Arvind Sankar <nivedita@...m.mit.edu>,
        Eric Dumazet <eric.dumazet@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Shaokun Zhang <zhangshaokun@...ilicon.com>,
        David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, jinyuqi@...wei.com,
        kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org, edumazet@...gle.com,
        guoyang2@...wei.com, Will Deacon <will@...nel.org>
Subject: Re: [PATCH] net: optimize cmpxchg in ip_idents_reserve



On 1/17/20 10:38 AM, Arvind Sankar wrote:
> On Fri, Jan 17, 2020 at 10:16:45AM -0800, Eric Dumazet wrote:
>> Wasńt it the case back in 2016 already for linux-4.8 ?
>>
>> What will prevent someone to send another report to netdev/lkml ?
>>
>>  -fno-strict-overflow support is not a prereq for CONFIG_UBSAN.
>>
>> Fact that we kept in lib/ubsan.c and lib/test_ubsan.c code for 
>> test_ubsan_add_overflow() and test_ubsan_sub_overflow() is disturbing.
>>
> 
> No, it was bumped in 2018 in commit cafa0010cd51 ("Raise the minimum
> required gcc version to 4.6"). That raised it from 3.2 -> 4.6.
> 

This seems good to me, for gcc at least.

Maybe it is time to enfore -fno-strict-overflow in KBUILD_CFLAGS 
instead of making it conditional.

Thanks.