[U-Boot] [RFC PATCH v2] u-boot: remove driver lookup loop from env_save()

[Simon Goldschmidt]

On 12.07.2018 14:32, Nicholas wrote:
> On gio, 2018-07-12 at 13:02 +0200, Simon Goldschmidt wrote:
>>
>> On 12.07.2018 12:52, Nicholas Faustini wrote:
>>>
>>> When called with ENVOP_SAVE, env_get_location() only returns the
>>> gd->env_load_location variable without actually checking for
>>> the environment location and priority.
>>>
>>> This behaviour causes env_save() to fall into an infinite loop when
>>> the low-level drv->save() call fails.
>>>
>>> The env_save() function should not loop through the environment
>>> location list but it should save the environment into the location
>>> stored in gd->env_load_location by the last env_load() call.
>>>
>>> Signed-off-by: Nicholas Faustini <nicholas.faustini at azcomtech.com>
>>> ---
>>>
>>> Changes in v2:
>>> - Restore gd->env_load_location to the highest priority location
>>> when
>>>     env_load() fails
>>>
>>>    env/env.c | 10 ++++++----
>>>    1 file changed, 6 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/env/env.c b/env/env.c
>>> index 5c0842a..18eb78d 100644
>>> --- a/env/env.c
>>> +++ b/env/env.c
>>> @@ -205,22 +205,24 @@ int env_load(void)
>>>    			return 0;
>>>    	}
>>>    
>>> +	env_get_location(ENVOP_LOAD, 0);
>> A comment why this is required would be good, I guess.
> Sure, I thought the same but eventually I didn't put it. Will do in the
> next version.
>>
>>>
>>> +
>>>    	return -ENODEV;
>>>    }
>>>    
>>>    int env_save(void)
>>>    {
>>>    	struct env_driver *drv;
>>> -	int prio;
>>>    
>>> -	for (prio = 0; (drv = env_driver_lookup(ENVOP_SAVE,
>>> prio)); prio++) {
>>> +	drv = env_driver_lookup(ENVOP_SAVE, 0);
>> Thinking again about this, would it make more sense to store
>> 'env_load_prio' in 'gd' after successful load? That way,
>> 'env_get_location()' would be more straightforward (no special case
>> for
>> ENVOP_SAVE) and here in 'env_save()' we could just write something
>> like
>> this:
>>
>> drv = env_driver_lookup(ENVOP_SAVE, gd->env_load_prio);
>>
>>
> I really like the 'env_load_prio' idea. But I also like having the
> special case for ENVOP_SAVE in env_get_location() as it enforces the
> fact that the location of 'save' is bound to the location of previous
> 'load'.
> I however don't have a strong opinion on this. I could even remove the
> whole switch() statement if we introduce 'env_load_prio'.

Me neither. I just thought it would be strange if env_get_location() was 
always called with prio 0.

> Also, I have some doubts about what it should be returned when !drv-
>> save and !env_has_inited(drv->location) (below)... I put -ENODEV but I
> don't like it so much.

I guess that's OK since it was like that before. And after all, the only 
place where the return value of env_save() is checked (do_env_save()), 
the exact error is ignored.

Simon

> 
>> Simon
>>
>>>
>>> +	if (drv) {
>>>    		int ret;
>>>    
>>>    		if (!drv->save)
>>> -			continue;
>>> +			return -ENODEV;
>>>    
>>>    		if (!env_has_inited(drv->location))
>>> -			continue;
>>> +			return -ENODEV;
>>>    
>>>    		printf("Saving Environment to %s... ", drv-
>>>> name);
>>>    		ret = drv->save();
>>>
>