[PATCH RFC] usb gadget: introduce usb_gadget_probe_driver
m.nazarewicz at samsung.com
Sat Jul 31 02:08:23 EST 2010
On Fri, 30 Jul 2010 17:26:02 +0200, Uwe Kleine-König <u.kleine-koenig at pengutronix.de> wrote:
> On Fri, Jul 30, 2010 at 05:16:46PM +0200, Michał Nazarewicz wrote:
>> On Fri, 30 Jul 2010 16:49:14 +0200, Uwe Kleine-König <u.kleine-koenig at pengutronix.de> wrote:
>>> This is like usb_gadget_register_driver with the only difference that it
>>> gets the bind function as parameter instead of using driver->bind. This
>>> allows fixing section mismatches like
>>> WARNING: drivers/usb/gadget/g_printer.o(.data+0xc): Section mismatch in
>>> reference from the variable printer_driver to the function
>>> The variable printer_driver references
>>> the function __init printer_bind()
>>> by using usb_gadget_probe_driver with driver->bind = NULL. When all
>>> drivers are fixed to use the new function the bind member of struct
>>> usb_gadget_driver can go away.
>>> Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
>>> Cc: Michal Nazarewicz <m.nazarewicz at samsung.com>
>>> Cc: Greg Kroah-Hartman <gregkh at suse.de>
BTW. Dunno if there is a reason to put me on Cc and Greg will be in
>>> there is an alternative patch in Greg's tree , but IMHO mine is
>>> better as it doesn't need __ref.
>> Personally I don't see advantage of this over changing the __init to __ref.
>> Or am I missing something? I see your patch as an unnecessary API change.
>> The way I understand it, __ref was introduced exactly for cases like this
>> one where function is referenced from "normal" data but used only during
>> init. Could you try to clarify for me why you think your solution is
>> better then mine?
> - Using __ref instead of __init moves all bind functions from .init.text
> to .text and so the code isn't freed after booting or module loading.
> (OK, you could fix this by marking the driver structs as __ref and
> keep __init for the bind functions.)
I believe this to be untrue. __ref puts code in .ref.text which AFAIK is
> - Using __ref might hide section mismatches. (Your patch hasn't this
> problem as the bind functions used to live in .init.text, so any
> reference to .init should be OK assuming that it was OK to live in
> .init.text in the first place. But when marking the driver structs
> this is an issue.) That's why I don't like __ref and said my patch
> were better as it doesn't make use of it.
> - The bind functions are only called at init time, so there is no need
> to save a pointer to it.
OK, I see some merit in this approach. However, the same issue is with
usb_configuration and ?usb_composite_driver -- those should be changed
in the same way or it would defeat the purpose of the patch.
Best regards, _ _
| Humble Liege of Serenely Enlightened Majesty of o' \,=./ `o
| Computer Science, Michał "mina86" Nazarewicz (o o)
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