linux-kernel - Re: [PATCH 3/5] Drivers: hv: kvp: Fix the recent regression caused by incorrect clean-up

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Message-ID: <20181017050705.GE22447@kroah.com>
Date:   Wed, 17 Oct 2018 07:07:05 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     kys@...rosoft.com
Cc:     linux-kernel@...r.kernel.org, devel@...uxdriverproject.org,
        olaf@...fle.de, apw@...onical.com, jasowang@...hat.com,
        sthemmin@...rosoft.com, Michael.H.Kelley@...rosoft.com,
        vkuznets@...hat.com, Haiyang Zhang <haiyangz@...rosoft.com>,
        Stable@...r.kernel.org
Subject: Re: [PATCH 3/5] Drivers: hv: kvp: Fix the recent regression caused
 by incorrect clean-up

On Wed, Oct 17, 2018 at 03:14:04AM +0000, kys@...uxonhyperv.com wrote:
> From: Dexuan Cui <decui@...rosoft.com>
> 
> In kvp_send_key(), we do need call process_ib_ipinfo() if
> message->kvp_hdr.operation is KVP_OP_GET_IP_INFO, because it turns out
> the userland hv_kvp_daemon needs the info of operation, adapter_id and
> addr_family. With the incorrect fc62c3b1977d, the host can't get the
> VM's IP via KVP.
> 
> And, fc62c3b1977d added a "break;", but actually forgot to initialize
> the key_size/value in the case of KVP_OP_SET, so the default key_size of
> 0 is passed to the kvp daemon, and the pool files
> /var/lib/hyperv/.kvp_pool_* can't be updated.
> 
> This patch effectively rolls back the previous fc62c3b1977d, and
> correctly fixes the "this statement may fall through" warnings.
> 
> This patch is tested on WS 2012 R2 and 2016.
> 
> Fixes: fc62c3b1977d ("Drivers: hv: kvp: Fix two "this statement may fall through" warnings")
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> Cc: K. Y. Srinivasan <kys@...rosoft.com>
> Cc: Haiyang Zhang <haiyangz@...rosoft.com>
> Cc: Stephen Hemminger <sthemmin@...rosoft.com>
> Cc: <Stable@...r.kernel.org>
> Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> ---
>  drivers/hv/hv_kvp.c | 26 ++++++++++++++++++++++----
>  1 file changed, 22 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
> index a7513a8a8e37..9fbb15c62c6c 100644
> --- a/drivers/hv/hv_kvp.c
> +++ b/drivers/hv/hv_kvp.c
> @@ -353,6 +353,9 @@ static void process_ib_ipinfo(void *in_msg, void *out_msg, int op)
>  
>  		out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;
>  
> +		__attribute__ ((fallthrough));

The comment should be sufficient for this, right?  I haven't seen many
uses of this attribute before, how common is it?


> +
> +	case KVP_OP_GET_IP_INFO:
>  		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
>  				MAX_ADAPTER_ID_SIZE,
>  				UTF16_LITTLE_ENDIAN,
> @@ -405,7 +408,11 @@ kvp_send_key(struct work_struct *dummy)
>  		process_ib_ipinfo(in_msg, message, KVP_OP_SET_IP_INFO);
>  		break;
>  	case KVP_OP_GET_IP_INFO:
> -		/* We only need to pass on message->kvp_hdr.operation.  */
> +		/*
> +		 * We only need to pass on the info of operation, adapter_id
> +		 * and addr_family to the userland kvp daemon.
> +		 */
> +		process_ib_ipinfo(in_msg, message, KVP_OP_GET_IP_INFO);
>  		break;
>  	case KVP_OP_SET:
>  		switch (in_msg->body.kvp_set.data.value_type) {
> @@ -446,9 +453,9 @@ kvp_send_key(struct work_struct *dummy)
>  
>  		}
>  
> -		break;
> -
> -	case KVP_OP_GET:
> +		/*
> +		 * The key is always a string - utf16 encoding.
> +		 */
>  		message->body.kvp_set.data.key_size =
>  			utf16s_to_utf8s(
>  			(wchar_t *)in_msg->body.kvp_set.data.key,
> @@ -456,6 +463,17 @@ kvp_send_key(struct work_struct *dummy)
>  			UTF16_LITTLE_ENDIAN,
>  			message->body.kvp_set.data.key,
>  			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
> +
> +		break;
> +
> +	case KVP_OP_GET:
> +		message->body.kvp_get.data.key_size =
> +			utf16s_to_utf8s(
> +			(wchar_t *)in_msg->body.kvp_get.data.key,
> +			in_msg->body.kvp_get.data.key_size,
> +			UTF16_LITTLE_ENDIAN,
> +			message->body.kvp_get.data.key,
> +			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;

Worst indentation ever :(

Yeah, I know it follows the others above it, but you should reconsider
it in the future...

thanks,

greg k-h