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

[subashab@codeaurora.org]

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.