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

[Joe Hershberger]

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.

-Joe