Re: [PATCH v1 01/25] net: core: device_rename: Use rwsem instead of a seqcount

[Eric Dumazet]

On 5/19/20 7:57 PM, David Miller wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Date: Wed, 20 May 2020 01:42:30 +0200
> 
>> Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> writes:
>>> On Wed, 20 May 2020 00:23:48 +0200
>>> Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>>>> No. We did not. -ENOTESTCASE
>>>
>>> Please try, it isn't that hard..
>>>
>>> # time for ((i=0;i<1000;i++)); do ip li add dev dummy$i type dummy; done
>>>
>>> real	0m17.002s
>>> user	0m1.064s
>>> sys	0m0.375s
>>
>> And that solves the incorrectness of the current code in which way?
> 
> You mentioned that there wasn't a test case, he gave you one to try.
> 

I do not think this would ever use device rename, nor netdev_get_name()

None of this stuff is fast path really.

# time for ((i=1;i<1000;i++)); do ip li add dev dummy$i type dummy; done

real	0m1.127s
user	0m0.270s
sys	0m1.039s