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Subject[PATCH 1/1] sh: add support for cmpxchg on u8 and u16 pointers
Date
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.

Do these function need to be impletmented in each header
simulataneously?

Thanks,
Liam

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;
--
2.27.0
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