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Subject: Re: [PATCH] nbd: add missing definition of pr_fmt
To:     Yu Kuai <yukuai1@huaweicloud.com>, Joe Perches <joe@perches.com>,
        <josef@toxicpanda.com>, <axboe@kernel.dk>, <houtao1@huawei.com>
CC:     <linux-block@vger.kernel.org>, <nbd@other.debian.org>,
        <linux-kernel@vger.kernel.org>, <yi.zhang@huawei.com>
References: <20220706093320.1962871-1-yukuai1@huaweicloud.com>
 <853a5164-78cf-1ccb-8e18-cff5b5bce4ff@huaweicloud.com>
 <49a8099eb7dd01e9d2d190056171341d87cd442b.camel@perches.com>
 <0dba2f0c-ba02-853e-60e7-873eabedcd80@huaweicloud.com>
From:   Yu Kuai <yukuai3@huawei.com>
Message-ID: <4e6a80cb-63fa-660c-8acf-f25062800238@huawei.com>
Date:   Sat, 23 Jul 2022 10:14:30 +0800
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Hi!

在 2022/07/20 19:46, Yu Kuai 写道:
> Hi !
> 
> 在 2022/07/18 22:32, Joe Perches 写道:
>> On Mon, 2022-07-18 at 21:52 +0800, Yu Kuai wrote:
>>> 在 2022/07/06 17:33, Yu Kuai 写道:
>>>> From: Yu Kuai <yukuai3@huawei.com>
>>>>
>>>> commit 1243172d5894 ("nbd: use pr_err to output error message") tries
>>>> to define pr_fmt and use short pr_err() to output error message,
>>>> however, the definition is missed.
>>> friendly ping ...
>> []
>>>> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
>> []
>>>> @@ -44,6 +44,9 @@
>>>>    #include <linux/nbd-netlink.h>
>>>>    #include <net/genetlink.h>
>>>> +#undef pr_fmt
>>>> +#define pr_fmt(fmt) "nbd: " fmt
>>>> +

I tried to remove the #undef:

--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -44,7 +44,6 @@
  #include <linux/nbd-netlink.h>
  #include <net/genetlink.h>

  #define pr_fmt(fmt) "nbd: " fmt

And then following warning is triggered:

drivers/block/nbd.c:47: warning: "pr_fmt" redefined
    47 | #define pr_fmt(fmt) "nbd: " fmt

It semms that keeping that #undef is the right thing to do.

Thanks,
Kuai
>> Typically, this #define is place before all #include lines
>> so there is no need for an #undef
> 
> Thanks for you advice, I'll do that in v2.
> 
> Kuai
> 
> .
>