RE: [PATCH] Revert "nvme-fc: fold t fc_update_appid into fc_appid_store"

[Muneendra Kumar M <muneendra.kumar@broadcom.com>]

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I have tested the below changes suggested by Christoph and it is working as
expected.


Tested-by: <muneendra.kumar@broadcom.com>



-----Original Message-----
From: James Smart [mailto:jsmart2021@gmail.com]
Sent: Tuesday, August 2, 2022 2:33 AM
To: Christoph Hellwig <hch@lst.de>; Ewan D. Milne <emilne@redhat.com>
Cc: linux-nvme@lists.infradead.org; muneendra.kumar@broadcom.com;
james.smart@broadcom.com; stable@vger.kernel.org
Subject: Re: [PATCH] Revert "nvme-fc: fold t fc_update_appid into
fc_appid_store"

On 8/1/2022 11:27 AM, Christoph Hellwig wrote:
> On Mon, Aug 01, 2022 at 12:27:13PM -0400, Ewan D. Milne wrote:
>> This reverts commit c814153c83a892dfd42026eaa661ae2c1f298792.
>>
>> The commit c814153c83a8 "nvme-fc: fold t fc_update_appid into
>> fc_appid_store"
>> changed the userspace interface, because the code that decrements "count"
>> to remove a trailing '\n' in the parsing results in the decremented
>> value being incorrectly be returned from the sysfs write.  Fix this by
>> revering the commit.
>
> Wouldn't something like the patch below be much simpler and cleaner:
>
>
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c index
> 9987797620b6d..e24ab688f00d5 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -3878,6 +3878,7 @@ static int fc_parse_cgrpid(const char *buf, u64 *id)
>   static ssize_t fc_appid_store(struct device *dev,
>   		struct device_attribute *attr, const char *buf, size_t count)
>   {
> +	size_t orig_count = count;
>   	u64 cgrp_id;
>   	int appid_len = 0;
>   	int cgrpid_len = 0;
> @@ -3902,7 +3903,7 @@ static ssize_t fc_appid_store(struct device *dev,
>   	ret = blkcg_set_fc_appid(app_id, cgrp_id, sizeof(app_id));
>   	if (ret < 0)
>   		return ret;
> -	return count;
> +	return orig_count;
>   }
>   static DEVICE_ATTR(appid_store, 0200, NULL, fc_appid_store);
>   #endif /* CONFIG_BLK_CGROUP_FC_APPID */
>

Reviewed-by: James Smart <jsmart2021@gmail.com>

looks good on my end.

-- james

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