Re: [Outreachy kernel] Re: [PATCH] Staging: fwserial: Convert macro into an inline function

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Mar 07, 2019 at 09:08:53PM +0100, Julia Lawall wrote:
> 
> 
> On Thu, 7 Mar 2019, Greg KH wrote:
> 
> > On Wed, Mar 06, 2019 at 04:48:09PM -0600, Madhumitha Prabakaran wrote:
> > > Convert macro into an inline function to make codebase better
> > >
> > > Signed-off-by: Madhumitha Prabakaran <madhumithabiw@gmail.com>
> > > ---
> > >  drivers/staging/fwserial/fwserial.c | 5 ++++-
> > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c
> > > index a1b90ea7fcb8..aec0f19597a9 100644
> > > --- a/drivers/staging/fwserial/fwserial.c
> > > +++ b/drivers/staging/fwserial/fwserial.c
> > > @@ -19,7 +19,10 @@
> > >
> > >  #include "fwserial.h"
> > >
> > > -#define be32_to_u64(hi, lo)  ((u64)be32_to_cpu(hi) << 32 | be32_to_cpu(lo))
> > > +inline u64 be32_to_u64(__be32 hi, __be32 lo)
> > > +{
> > > +	return ((u64)be32_to_cpu(hi) << 32 | be32_to_cpu(lo));
> > > +}
> >
> > For some reason I thought the kernel had a function that already did
> > this, but it doesn't, which is really odd.  Anyway, that's something
> > that could be done in the future, as this is done all over the place in
> > different drivers.
> 
> Actually, as far as I can see, only two occurrences, in
> drivers/target/sbp/sbp_target.c and
> drivers/net/ethernet/mellanox/mlxfw/mlxfw_mfa2.c
> 
> Perhaps there are some other variants that are more popular.

The file include/linux/io-64-nonatomic-hi-lo.h open-codes this 4
different times, as does include/linux/ml5/device.h and then there is
HILO_GEN() which tries to do the right thing for this type of macro, but
it's specific to a single driver.

Odds are it is also open-coded in many other drivers as well :(

thanks,

greg k-h