From: Tariq Toukan <ttoukan.linux@gmail.com>
To: David Miller <davem@davemloft.net>, luojiaxing@huawei.com
Cc: kuba@kernel.org, idos@mellanox.com, ogerlitz@mellanox.com,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linuxarm@huawei.com
Subject: Re: [PATCH net-next] net: ethernet: mlx4: Avoid assigning a value to ring_cons but not used it anymore in mlx4_en_xmit()
Date: Sun, 13 Sep 2020 13:12:05 +0300 [thread overview]
Message-ID: <c0987225-0079-617a-bf89-b672b07f298a@gmail.com> (raw)
In-Reply-To: <20200912.182219.1013721666435098048.davem@davemloft.net>
On 9/13/2020 4:22 AM, David Miller wrote:
> From: Luo Jiaxing <luojiaxing@huawei.com>
> Date: Sat, 12 Sep 2020 16:08:15 +0800
>
>> We found a set but not used variable 'ring_cons' in mlx4_en_xmit(), it will
>> cause a warning when build the kernel. And after checking the commit record
>> of this function, we found that it was introduced by a previous patch.
>>
>> So, We delete this redundant assignment code.
>>
>> Fixes: 488a9b48e398 ("net/mlx4_en: Wake TX queues only when there's enough room")
>>
>> Signed-off-by: Luo Jiaxing <luojiaxing@huawei.com>
>
> Looks good, applied, thanks.
>
Hi Luo,
I didn't get a chance to review it during the weekend.
The ring_cons local variable is used in line 903:
https://elixir.bootlin.com/linux/v5.9-rc4/source/drivers/net/ethernet/mellanox/mlx4/en_tx.c#L903
AVG_PERF_COUNTER depends on the compile-time definition of
MLX4_EN_PERF_STAT. Otherwise it is a nop.
1. Your patch causes a degradation to the case when MLX4_EN_PERF_STAT is
defined.
2. When MLX4_EN_PERF_STAT is not defined, we should totally remove the
local variable declaration, not only its usage.
Please let me know if you're planning to fix this. Otherwise I'll do.
Regards,
Tariq
next prev parent reply other threads:[~2020-09-13 10:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-12 8:08 Luo Jiaxing
2020-09-13 1:22 ` David Miller
2020-09-13 10:12 ` Tariq Toukan [this message]
2020-09-13 21:33 ` David Miller
2020-09-14 20:02 ` Jakub Kicinski
2020-09-15 12:06 ` Tariq Toukan
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