[PATCH net] net: qualcomm: rmnet: Allow configuration updates to existing devices

[PATCH net] net: qualcomm: rmnet: Allow configuration updates to existing devices

[Subash Abhinov Kasiviswanathan]

This allows the changelink operation to succeed if the mux_id was
specified as an argument. Note that the mux_id must match the
existing mux_id of the rmnet device or should be an unused mux_id.

Fixes: 1dc49e9d164c ("net: rmnet: do not allow to change mux id if mux id is duplicated")
Reported-by: Alex Elder <elder@linaro.org>
Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
---
 .../ethernet/qualcomm/rmnet/rmnet_config.c    | 21 ++++++++++++-------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
index fbf4cbcf1a65..06332984399d 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
@@ -294,19 +294,24 @@ static int rmnet_changelink(struct net_device *dev, struct nlattr *tb[],
 
 	if (data[IFLA_RMNET_MUX_ID]) {
 		mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
-		if (rmnet_get_endpoint(port, mux_id)) {
-			NL_SET_ERR_MSG_MOD(extack, "MUX ID already exists");
-			return -EINVAL;
-		}
 		ep = rmnet_get_endpoint(port, priv->mux_id);
 		if (!ep)
 			return -ENODEV;
 
-		hlist_del_init_rcu(&ep->hlnode);
-		hlist_add_head_rcu(&ep->hlnode, &port->muxed_ep[mux_id]);
+		if (mux_id != priv->mux_id) {
+			if (rmnet_get_endpoint(port, mux_id)) {
+				NL_SET_ERR_MSG_MOD(extack,
+						   "MUX ID already exists");
+				return -EINVAL;
+			}
 
-		ep->mux_id = mux_id;
-		priv->mux_id = mux_id;
+			hlist_del_init_rcu(&ep->hlnode);
+			hlist_add_head_rcu(&ep->hlnode,
+					   &port->muxed_ep[mux_id]);
+
+			ep->mux_id = mux_id;
+			priv->mux_id = mux_id;
+		}
 	}
 
 	if (data[IFLA_RMNET_FLAGS]) {
-- 
2.26.0

Re: [PATCH net] net: qualcomm: rmnet: Allow configuration updates to existing devices

[Alex Elder]

On 3/31/20 5:43 PM, Subash Abhinov Kasiviswanathan wrote:
> This allows the changelink operation to succeed if the mux_id was
> specified as an argument. Note that the mux_id must match the
> existing mux_id of the rmnet device or should be an unused mux_id.
> 
> Fixes: 1dc49e9d164c ("net: rmnet: do not allow to change mux id if mux id is duplicated")
> Reported-by: Alex Elder <elder@linaro.org>
> Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>

This was a regression in 5.6, and got back-ported to 5.5.11 and
possibly further back.  Please be sure the fix gets applied to
stable branches if appropriate.

If you happen to post a second version of this I have a suggestion,
below.  But the patch looks OK to me as-is.

Thanks.

Tested-by: Alex Elder <elder@linaro.org>

> ---
>  .../ethernet/qualcomm/rmnet/rmnet_config.c    | 21 ++++++++++++-------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
> index fbf4cbcf1a65..06332984399d 100644
> --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
> +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
> @@ -294,19 +294,24 @@ static int rmnet_changelink(struct net_device *dev, struct nlattr *tb[],
>  
>  	if (data[IFLA_RMNET_MUX_ID]) {
>  		mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
> -		if (rmnet_get_endpoint(port, mux_id)) {
> -			NL_SET_ERR_MSG_MOD(extack, "MUX ID already exists");
> -			return -EINVAL;
> -		}

My suggestion is this:  Since the endpoint pointer isn't used
outside the "if (mux_id != priv->mux_id)" block, you could
do the lookup inside that block.

>  		ep = rmnet_get_endpoint(port, priv->mux_id);
>  		if (!ep)
>  			return -ENODEV;
>  
> -		hlist_del_init_rcu(&ep->hlnode);
> -		hlist_add_head_rcu(&ep->hlnode, &port->muxed_ep[mux_id]);
> +		if (mux_id != priv->mux_id) {
> +			if (rmnet_get_endpoint(port, mux_id)) {
> +				NL_SET_ERR_MSG_MOD(extack,
> +						   "MUX ID already exists");
> +				return -EINVAL;
> +			}
>  
> -		ep->mux_id = mux_id;
> -		priv->mux_id = mux_id;
> +			hlist_del_init_rcu(&ep->hlnode);
> +			hlist_add_head_rcu(&ep->hlnode,
> +					   &port->muxed_ep[mux_id]);
> +
> +			ep->mux_id = mux_id;
> +			priv->mux_id = mux_id;
> +		}
>  	}
>  
>  	if (data[IFLA_RMNET_FLAGS]) {
> 

Re: [PATCH net] net: qualcomm: rmnet: Allow configuration updates to existing devices

[subashab]

On 2020-03-31 18:06, Alex Elder wrote:
> On 3/31/20 5:43 PM, Subash Abhinov Kasiviswanathan wrote:
>> This allows the changelink operation to succeed if the mux_id was
>> specified as an argument. Note that the mux_id must match the
>> existing mux_id of the rmnet device or should be an unused mux_id.
>> 
>> Fixes: 1dc49e9d164c ("net: rmnet: do not allow to change mux id if mux 
>> id is duplicated")
>> Reported-by: Alex Elder <elder@linaro.org>
>> Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
>> Signed-off-by: Subash Abhinov Kasiviswanathan 
>> <subashab@codeaurora.org>
> 
> This was a regression in 5.6, and got back-ported to 5.5.11 and
> possibly further back.  Please be sure the fix gets applied to
> stable branches if appropriate.
> 
> If you happen to post a second version of this I have a suggestion,
> below.  But the patch looks OK to me as-is.
> 
> Thanks.
> 
> Tested-by: Alex Elder <elder@linaro.org>
> 
>> ---
>>  .../ethernet/qualcomm/rmnet/rmnet_config.c    | 21 
>> ++++++++++++-------
>>  1 file changed, 13 insertions(+), 8 deletions(-)
>> 
>> diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c 
>> b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
>> index fbf4cbcf1a65..06332984399d 100644
>> --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
>> +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
>> @@ -294,19 +294,24 @@ static int rmnet_changelink(struct net_device 
>> *dev, struct nlattr *tb[],
>> 
>>  	if (data[IFLA_RMNET_MUX_ID]) {
>>  		mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
>> -		if (rmnet_get_endpoint(port, mux_id)) {
>> -			NL_SET_ERR_MSG_MOD(extack, "MUX ID already exists");
>> -			return -EINVAL;
>> -		}
> 
> My suggestion is this:  Since the endpoint pointer isn't used
> outside the "if (mux_id != priv->mux_id)" block, you could
> do the lookup inside that block.

I've sent a v2 now based on your comment.

Re: [PATCH net] net: qualcomm: rmnet: Allow configuration updates to existing devices

[David Miller]

From: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Date: Tue, 31 Mar 2020 16:43:48 -0600

> This allows the changelink operation to succeed if the mux_id was
> specified as an argument. Note that the mux_id must match the
> existing mux_id of the rmnet device or should be an unused mux_id.
> 
> Fixes: 1dc49e9d164c ("net: rmnet: do not allow to change mux id if mux id is duplicated")
> Reported-by: Alex Elder <elder@linaro.org>
> Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>

Applied, thanks.