[PATCH] mISDN: avoid arch specific __builtin_return_address call

[davem@davemloft.net (David Miller)]

From: Arnd Bergmann <arnd@arndb.de>
Date: Tue, 13 Jan 2015 17:10:58 +0100

> Not all architectures are able to call __builtin_return_address().
> On ARM, the mISDN code produces this warning:
> 
> hardware/mISDN/w6692.c: In function 'w6692_dctrl':
> hardware/mISDN/w6692.c:1181:75: warning: unsupported argument to '__builtin_return_address'
>   pr_debug("%s: %s dev(%d) open from %p\n", card->name, __func__,
>                                                                            ^
> hardware/mISDN/mISDNipac.c: In function 'open_dchannel':
> hardware/mISDN/mISDNipac.c:759:75: warning: unsupported argument to '__builtin_return_address'
>   pr_debug("%s: %s dev(%d) open from %p\n", isac->name, __func__,
>                                                                            ^
> 
> In a lot of cases, this is relatively easy to work around by
> passing the value of __builtin_return_address(0) from the
> callers into the functions that want it. One exception is
> the indirect 'open' function call in struct isac_hw. While it
> would be possible to fix this as well, this patch only addresses
> the other callers properly and lets this one return the direct
> parent function, which should be good enough.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Applied.