Re: [wireless-next:master 169/199] drivers/net/wireless/brcm80211/brcmfmac/dhd_sdio.c:2469:3: error: implicit declaration of function 'atomic_set_mask'

[Arend van Spriel]

On 02/28/14 23:44, Florian Fainelli wrote:
> 2014-02-28 14:33 GMT-08:00 Arend van Spriel<arend@xxxxxxxxxxxx>:
> > On 02/28/2014 11:26 PM, Florian Fainelli wrote:
> > > 2014-02-28 14:22 GMT-08:00 Arend van Spriel<arend@xxxxxxxxxxxx>:
> > > > On 02/28/2014 11:15 PM, kbuild test robot wrote:
> > > > > tree:   git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next.git master
> > > > > head:   3e3831c4fdc53aabf3a56419ef6d96a841c52435
> > > > > commit: c98db0bec72ac7ef127119c1ed962d6f56802b12 [169/199] brcmfmac: Use atomic functions for intstatus update.
> > > > > config: make ARCH=ia64 allmodconfig
> > > > >
> > > > > All error/warnings:
> > > > >
> > > > >     drivers/net/wireless/brcm80211/brcmfmac/dhd_sdio.c: In function 'brcmf_sdio_intr_rstatus':
> > > > > > > drivers/net/wireless/brcm80211/brcmfmac/dhd_sdio.c:2469:3: error: implicit declaration of function 'atomic_set_mask' [-Werror=implicit-function-declaration]
> > > > >     cc1: some warnings being treated as errors
> > > >
> > > > Hi Fengguang,
> > > >
> > > > So atomic_set_mask() is not a generally available function. I thought
> > > > that if the arch does not provide it, the asm-generic implementation is
> > > > used.
> > >
> > > Though so as well.
> > >
> > > > Also it seems the function prototype is not the same for all
> > > > archs. :-(
> > >
> > > This does not sound like it is expected, and this might need fixing,
> > > do you want to tackle this?
> >
> > I got email m68k and ia64 failing. Some implementations are in assembly.
> > It has been (counting...) over 20 years since I did some baby steps in
> > m68k assembly and do not really feel a strong pull to that dark side.
>
> This is supposed to be a generic function that everyone should be able
> to use without knowing the underlying details. Not quite sure why
> those two architectures are different, maybe we should ask Geert and
> Tony about this?

I was about to when I decided to do some more digging. So taking a 
closer look at include/asm-generic/atomic.h revealed this:

/*
 * Generic C implementation of atomic counter operations. Usable on
 * UP systems only. Do not include in machine independent code.

And further down:

#ifdef CONFIG_SMP
/* Force people to define core atomics */
# if !defined(atomic_add_return) || !defined(atomic_sub_return) || \
     !defined(atomic_clear_mask) || !defined(atomic_set_mask)
#  error "SMP requires a little arch-specific magic"
# endif
#endif

So in these SMP era architecture specific implementations seem required. 
IA64 does not provide it (so CONFIG_SMP not supported?) and m68k has 
different prototype. Apparently, the comment /* Force people to define 
core atomics */ did not fly for all archs (yet) :-p.

Regards,
Arend
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