[U-Boot] [PATCH] net: Allow setenv to set net global variables

[Chris Packham]

On 06/14/2016 10:19 AM, Joe Hershberger wrote:
> Hi Chris,
>
> On Mon, Jun 13, 2016 at 4:13 PM, Chris Packham
> <Chris.Packham at alliedtelesis.co.nz> wrote:
>> On 06/14/2016 06:34 AM, Joe Hershberger wrote:
>>> Hi Chris,
>>>
>>> On Sun, Jun 12, 2016 at 3:58 PM, Chris Packham
>>> <Chris.Packham at alliedtelesis.co.nz> wrote:
>>>> Hi Joe,
>>>>
>>>> On 06/11/2016 03:56 AM, Joe Hershberger wrote:
>>>>> On Thu, Jun 9, 2016 at 8:40 PM, Matthew Bright
>>>>> <matthew.bright at alliedtelesis.co.nz> wrote:
>>>>>> The patch fd3056337e6fcc introduces env callbacks to several of the net
>>>>>> related env variables. These callbacks are responsible for updating the
>>>>>> corresponding global variables internal to the net source code. However
>>>>>> this behavior will be skipped if the source of the callbacks originated
>>>>>> from setenv. This is based on the assumption that all current instances
>>>>>> of setenv are invoked using the same global variables that the callback
>>>>>> will eventually write to; therefore there is no need set them to the
>>>>>> same value.
>>>>>>
>>>>>> As setenv is a public interface this assumption may not always hold. In
>>>>>> our usage case we implement a user facing menu system for configuration
>>>>>> of networking parameters. This ultimately lead to calling setenv rather
>>>>>> than through the traditional interactive command line parser do_env_set.
>>>>>> Therefore, in our usage case, setenv can be called for an "interactive"
>>>>>> case. Consequently, the early return for non-interactive invocation are
>>>>>> now removed and any call to setenv will update the corresponding states
>>>>>> internal to the net source code as expected.
>>>>>>
>>>>>> Signed-off-by: Matthew Bright <matthew.bright at alliedtelesis.co.nz>
>>>>>> Reviewed-by: Hamish Martin <hamish.martin at alliedtelesis.co.nz>
>>>>>> Reviewed-by: Chris Packham <chris.packham at alliedtelesis.co.nz>
>>>>>> ---
>>>>>>     net/net.c | 24 ------------------------
>>>>>>     1 file changed, 24 deletions(-)
>>>>>>
>>>>>> diff --git a/net/net.c b/net/net.c
>>>>>> index 1e1d23d..726b0f0 100644
>>>>>> --- a/net/net.c
>>>>>> +++ b/net/net.c
>>>>>> @@ -209,9 +209,6 @@ int __maybe_unused net_busy_flag;
>>>>>>     static int on_bootfile(const char *name, const char *value, enum env_op op,
>>>>>>            int flags)
>>>>>>     {
>>>>>> -       if (flags & H_PROGRAMMATIC)
>>>>>> -               return 0;
>>>>>> -
>>>>>
>>>>> Why can't you just change your menu to call the API that is
>>>>> interactive instead of setenv?
>>>>
>>>> Which API are you referring to? _do_env_set() is static so the only
>>>> public api would be run_command("setenv ipaddr ...") or have I missed
>>>> something?
>>>
>>> Yes, that's what I was referring to.
>>>
>>> Another option would be to add an explicit function that provides this
>>> directly. Maybe even make a generic version that accepts a flags
>>> parameter, then implement the existing function as a call to this new
>>> function which passes in a "programmatic" flag.
>>>
>>
>> That's what I was thinking. Because setenv is one of the exported
>> functions for standalone applications I was wondering if instead of
>> setenv() passing H_PROGRAMMATIC we add prog_setenv() (naming things is
>> hard) for the net use-case since that is the only thing that currently
>> checks H_PROGRAMMATIC.
>
> That might be OK. The only reservation I have about it is that the
> setenv() function is generally a programmatic operation since only C
> code can get to it. Only in the case where you are implementing some
> more complex interaction (like your menu) is it not actually
> programmatic. I just worry about it being misleading in the future.
>

Agreed. My initial reaction was that our menu should be treated like 
H_INTERACTIVE but there wasn't an easy way to achieve this.

Do you have any feel for the direction of H_PROGRAMMATIC is going? Are 
we going to see more environment variables in other parts of the code 
that will get similar treatment.