Hi Andi, Nick,
On Wed, 09 Aug 2023 21:13:10 +0200, Andi Shyti wrote:
> On Tue, Aug 08, 2023 at 09:56:16AM -0700, Nick Desaulniers wrote:
> > I'm looking to enable -Wmissing-variable-declarations behind W=1. 0day
> > bot spotted the following instance:
> >
> > drivers/i2c/busses/i2c-amd756.c:286:20: warning: no previous extern
> > declaration for non-static variable 'amd756_smbus'
> > [-Wmissing-variable-declarations]
> > 286 | struct i2c_adapter amd756_smbus = {
> > | ^
> > drivers/i2c/busses/i2c-amd756.c:286:1: note: declare 'static' if the
> > variable is not intended to be used outside of this translation unit
> > 286 | struct i2c_adapter amd756_smbus = {
> > | ^
> >
> > This symbol is referenced by more than one translation unit, so create
> > then include the correct header for their declarations.
> >
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Closes: https://lore.kernel.org/llvm/202308081000.tTL1ElTr-lkp@xxxxxxxxx/
> > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
>
> You might want to have a Fixes tag here and
>
> Cc: Jean Delvare <jdelvare@xxxxxxxx>
Fixes tag would cause unnecessary worry, with people backporting the
patch while it doesn't actually fix anything. No need for that.
>
> [...]
>
> > --- /dev/null
> > +++ b/drivers/i2c/busses/i2c-amd756.h
> > @@ -0,0 +1,3 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
>
> Please, leave a space here.
>
> And you might also want to have something like:
>
> #ifndef __I2C_AMD_756_H__
> #define __I2C_AMD_756_H__
>
> > +#include <linux/i2c.h>
>
> space here.
>
> > +extern struct i2c_adapter amd756_smbus;
>
> #endif /* __I2C_AMD_756_H__ */
>
> Jean, any opinion on this patch, I don't really know this driver,
> but is there a way to avoid this extern declaration.
Thanks for your review. I would personally not bother with a header
file, this is unnecessary burden. Just add the extern declaration to
i2c-amd756.c as was already done in i2c-amd756-s4882.c. The whole thing
is a horrible hack anyway and there won't be more occurrences of it, so
the more simple it stays, the better.
Some history: I wrote the pseudo-driver i2c-amd756-s4882 when the
i2c-core did not yet support multiplexing. Nowadays, proper support
would be implemented using i2c-mux-* and i2c-amd756-s4882.c would go
away entirely. Actually, I very much doubt any of these 2007 Tyan
server boards is still in activity today, so maybe we should just
delete the driver.
Note that i2c-nforce2.c will need the same fix as struct i2c_adapter
nforce2_smbus is extern as well.
--
Jean Delvare
SUSE L3 Support
