[U-Boot] Problem with initialize in mmc_initialize in mmc.c

[Faiz Abbas]

On Monday 30 October 2017 07:37 PM, Faiz Abbas wrote:
> Hi,
> 
> The variable *initialized* in mmc_initialize() is declared as static and
> initialised to 0 in the following commit. This makes the compiler put it
> in the .bss section of the image.
> 
> commit 1b26bab12e85e8b0d382d6775e40d14445249574
> Author: Daniel Kochmański <dkochmanski at turtle-solutions.eu>
> Date:   Fri May 29 16:55:43 2015 +0200
> 
>     mmc: Protect `mmc_initialize` from initialising mmc multiple times
> 
>     `mmc_initialize` might be called multiple times leading to the
> mmc-controllers being initialised twice, and initialising the
> `mmc_devices` list head twice which may lead to memory leaks.
> 
>     Signed-off-by: Daniel Kochmański <dkochmanski at turtle-solutions.eu>
>     CC: Roy Spliet <r.spliet at ultimaker.com>
>     Cc: Ian Campbell <ijc at hellion.org.uk>
>     CC: Pantelis Antoniou <panto at antoniou-consulting.com>
>     Acked-by: Hans de Goede <hdegoede at redhat.com>
>     Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> 
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
> index da47037..f12546a 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -1762,6 +1762,11 @@ static void do_preinit(void)
> 
>  int mmc_initialize(bd_t *bis)
>  {
> +       static int initialized = 0;
> +       if (initialized)        /* Avoid initializing mmc multiple times */
> +               return 0;
> +       initialized = 1;
> +
>         INIT_LIST_HEAD (&mmc_devices);
>         cur_dev_num = 0;
> 
> 
> .bss should not be accessed in u-boot before relocation because it
> overlaps with fdt and writing to variables in .bss can corrupt the fdt.
> MMC can be probed before relocation if it contains the u-boot
> environment. Therefore, I tried to move this variable to the .data
> section by
> 
> static int initialized __attribute__((section(".data")));
> 
> When *initialized* was a part of .bss it was getting re-initilized to 0
> as a part of relocation. Therefore, mmc was getting probed again
> successfully after relocation with new addresses for mmc devices.
> 
> Now when *initialized* is not a part of .bss, it holds its value across
> relocation and a second call to mmc_initialize() returns without doing
> anything. However, the *mmc_devices* list containing pointers to the
> older locations of mmc devices is not refreshed and thus mmc devices
> fail to enumerate.
> 
> So *initialized* is a problem whether it is in .data or .bss.
> I am not sure how to fix this. Any help is appreciated.

I have been told that all pointers are supposed to be updated during
relocation. Can anyone point to relevant code or example of the same?

Thanks,
Faiz