On 2020/12/10 22:23, Geert Uytterhoeven wrote:

Hi Damien,

On Thu, Dec 10, 2020 at 1:36 PM Damien Le Moal [off-list ref] wrote:

quoted

On Thu, 2020-12-10 at 11:04 +0100, Geert Uytterhoeven wrote:

quoted

On Thu, Dec 10, 2020 at 4:41 AM Damien Le Moal [off-list ref] wrote:

quoted

Changes from v6:
* Annotate struct platform_driver variables with __refdata to avoid
  section mismatch compilation errors

Blindly following the advice from kernel test robot [off-list ref] is
not always a good idea:

    The variable k210_rst_driver references
    the function __init set_reset_devices()
    If the reference is valid then annotate the
    variable with or __refdata (see linux/init.h) or name the variable:

If your driver's probe function is annotated with __init, you cannot
have a pointer to it in the driver structure, as any binding done after
the freeing of initmem will cause a crash.  Adding the __refdata merely
suppresses the warning, and won't avoid the crash.

Hmm... I must be misunderstanding something here. free_initmem() is called from
kernel_init() right before starting the user init process. That is late enough
that all drivers are already probed and initialized. At least that is what I
thought, especially considering that none of the k210 drivers can be modules
and are all builtin. What am I missing here ?

For these specific cases, binding is indeed unlikely to happen after
free_initmem(). In the generic case that is not true.
However, you can still trigger it manually by unbinding and rebinding
the device manually through sysfs.

Got it. Sending a v8 with the correction.

Thanks !

quoted

So I think I will go with option 2. It is simpler and safer. We can always
revisit and optimize later. I would prefer this series to land first :)

Right. Correctness first, performance later.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

-- 
Damien Le Moal
Western Digital Research