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

[Simon Goldschmidt]

Hi,


Pepperl+Fuchs GmbH, Mannheim
Geschaeftsfuehrer/Managing Directors: Dr.-Ing. Gunther Kegel (Vors./CEO), Werner Guthier, Mehmet Hatiboglu
Vorsitzender des Aufsichtsrats/Chairman of the supervisory board: Michael Fuchs sen.
Registergericht/Register Court: AG Mannheim HRB 4713
On 10.07.2018 22:49, Simon Glass wrote:
> Hi Nicholas,
> 
> On 10 July 2018 at 06:57, Nicholas Faustini
> <nicholas.faustini at azcomtech.com> 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 allows saving the
>> environment into the same location that has been previously loaded.
>>
>> This behaviour causes env_save() to fall into an infinite loop when
>> the low-level drv->save() call fails.
> 
> Why is this? Should it not stop eventually? Do we need a limit on prio?

See my description in this mail:

https://lists.denx.de/pipermail/u-boot/2018-April/324728.html

Unfortunately, I got diverted at that time and could not follow up on 
this. Essentially, the question is raised what 'env save' is supposed to 
do with multiple environments.

Currently, env_save() effectively stores only to the location where the 
env has been loaded from, which is questionable. But storing to all 
locations or the default location might not be correct, either.

Maybe the 'env save' command might need a parameter the tells it where 
to save?

Regards,
Simon (Goldschmidt)

> 
>>
>> The env_save() function should not loop through the environment
>> location list but it should use the previously discovered
>> environment driver once.
> 
> What is that? It should be possible to write the env to multiple
> places. Also what is the previously discovered environment?
> 
>>
>> Signed-off-by: Nicholas Faustini <nicholas.faustini at azcomtech.com>
>> ---
>>
>>   env/env.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/env/env.c b/env/env.c
>> index 5c0842a..897d197 100644
>> --- a/env/env.c
>> +++ b/env/env.c
>> @@ -211,16 +211,16 @@ int env_load(void)
>>   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);
>> +       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();
>> --
>> 2.7.4
>>
> 
> Regards,
> Simon
> 

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