Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH 1/1] sh: add support for cmpxchg on u8 and u16 pointers | From | "Liam Beguin" <> | Date | Wed, 19 Aug 2020 09:23:47 -0400 |
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Hi Geert,
On Wed Aug 19, 2020 at 5:09 AM EDT, Geert Uytterhoeven wrote: > 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? >
Thanks for your feedback I'll have a look at the asm-generic functions and try to use those instead.
> > > > Do these function need to be impletmented in each header > > simulataneously? > > Yes, we need them for all variants. >
Okay, I'll look into that. Would you recommend a good way to test these changes?
> > 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
Thanks for your time, Liam
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