From: David Miller <davem@davemloft.net>
To: zhangshaokun@hisilicon.com
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
jinyuqi@huawei.com, kuznet@ms2.inr.ac.ru,
yoshfuji@linux-ipv6.org, kuba@kernel.org, jiri@resnulli.us,
nivedita@alum.mit.edu, peterz@infradead.org, edumazet@google.com,
jiongwang@huawei.com
Subject: Re: [PATCH v2] net: revert "net: get rid of an signed integer overflow in ip_idents_reserve()"
Date: Sun, 17 May 2020 12:34:37 -0700 (PDT) [thread overview]
Message-ID: <20200517.123437.2084818619487673025.davem@davemloft.net> (raw)
In-Reply-To: <1589600809-18001-1-git-send-email-zhangshaokun@hisilicon.com>
From: Shaokun Zhang <zhangshaokun@hisilicon.com>
Date: Sat, 16 May 2020 11:46:49 +0800
> From: Yuqi Jin <jinyuqi@huawei.com>
>
> Commit adb03115f459 ("net: get rid of an signed integer overflow in ip_idents_reserve()")
> used atomic_cmpxchg to replace "atomic_add_return" inside the function
> "ip_idents_reserve". The reason was to avoid UBSAN warning.
> However, this change has caused performance degrade and in GCC-8,
> fno-strict-overflow is now mapped to -fwrapv -fwrapv-pointer
> and signed integer overflow is now undefined by default at all
> optimization levels[1]. Moreover, it was a bug in UBSAN vs -fwrapv
> /-fno-strict-overflow, so Let's revert it safely.
>
> [1] https://gcc.gnu.org/gcc-8/changes.html
>
> Suggested-by: Peter Zijlstra <peterz@infradead.org>
> Suggested-by: Eric Dumazet <edumazet@google.com>
...
> Signed-off-by: Yuqi Jin <jinyuqi@huawei.com>
> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Applied, thanks.
prev parent reply other threads:[~2020-05-17 19:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-16 3:46 [PATCH v2] net: revert "net: get rid of an signed integer overflow in ip_idents_reserve()" Shaokun Zhang
2020-05-17 19:34 ` David Miller [this message]
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