Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Wed, 19 Aug 2020 11:09:46 +0200 | Subject | Re: [PATCH 1/1] sh: add support for cmpxchg on u8 and u16 pointers |
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Hi Liam,
On Wed, Aug 19, 2020 at 5:07 AM Liam Beguin <liambeguin@gmail.com> wrote: > The kernel test bot reported[1] that using set_mask_bits on a u8 causes > the following issue on SuperH: > > >> ERROR: modpost: "__cmpxchg_called_with_bad_pointer" [drivers/phy/ti/phy-tusb1210.ko] undefined! > > Add support for cmpxchg on u8 and u16 pointers. > > [1] https://lore.kernel.org/patchwork/patch/1288894/#1485536 > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Liam Beguin <liambeguin@gmail.com> > --- > > Hi, > > This was reported by the kernel test bot on an architecture I can't > really test on. I was only able to make sure the build succeeds, but > nothing more. > This patch is based on the __cmpxchg_u32 impletmentation and seems > incomplete based on the different cmpxchg headers I can find.
Indeed. This version is suitable for non-SMP machines only. BTW, it looks like this version can be replaced by the one in asm-generic?
> > Do these function need to be impletmented in each header > simulataneously?
Yes, we need them for all variants.
> arch/sh/include/asm/cmpxchg-irq.h | 27 +++++++++++++++++++++++++++ > arch/sh/include/asm/cmpxchg.h | 5 +++-- > 2 files changed, 30 insertions(+), 2 deletions(-) > > diff --git a/arch/sh/include/asm/cmpxchg-irq.h b/arch/sh/include/asm/cmpxchg-irq.h > index 07d3e7f08389..918c4153a930 100644 > --- a/arch/sh/include/asm/cmpxchg-irq.h > +++ b/arch/sh/include/asm/cmpxchg-irq.h > @@ -51,4 +51,31 @@ static inline unsigned long __cmpxchg_u32(volatile int *m, unsigned long old, > return retval; > } > > +static inline unsigned long __cmpxchg_u16(volatile u16 *m, unsigned long old, > + unsigned long new) > +{ > + u16 retval; > + unsigned long flags; > + > + local_irq_save(flags); > + retval = *m; > + if (retval == old) > + *m = new; > + local_irq_restore(flags); > + return (unsigned long)retval; > +} > + > +static inline unsigned long __cmpxchg_u8(volatile u8 *m, unsigned long old, > + unsigned long new) > +{ > + u8 retval; > + unsigned long flags; > + > + local_irq_save(flags); > + retval = *m; > + if (retval == old) > + *m = new; > + local_irq_restore(flags); > + return (unsigned long)retval; > +} > #endif /* __ASM_SH_CMPXCHG_IRQ_H */ > diff --git a/arch/sh/include/asm/cmpxchg.h b/arch/sh/include/asm/cmpxchg.h > index e9501d85c278..7d65d0fd1665 100644 > --- a/arch/sh/include/asm/cmpxchg.h > +++ b/arch/sh/include/asm/cmpxchg.h > @@ -56,8 +56,9 @@ static inline unsigned long __cmpxchg(volatile void * ptr, unsigned long old, > unsigned long new, int size) > { > switch (size) { > - case 4: > - return __cmpxchg_u32(ptr, old, new); > + case 4: return __cmpxchg_u32((int *)ptr, old, new); > + case 2: return __cmpxchg_u16((u16 *)ptr, old, new); > + case 1: return __cmpxchg_u8((u8 *)ptr, old, new); > } > __cmpxchg_called_with_bad_pointer(); > return old;
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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