On 17.04.2024 12:04, Oleksii Kurochko wrote:
> +/*
> + * This function doesn't exist, so you'll get a linker error
> + * if something tries to do an invalid xchg().
> + */
> +extern void __bad_xchg(volatile void *ptr, int size);
> +
> +static always_inline unsigned long __xchg(volatile void *ptr, unsigned long
> new, int size)
> +{
> + unsigned long ret;
> +
> + switch ( size )
> + {
> + case 1:
> + ret = emulate_xchg_1_2((volatile uint8_t *)ptr, new, ".aq", ".aqrl");
> + break;
> + case 2:
> + ret = emulate_xchg_1_2((volatile uint16_t *)ptr, new, ".aq",
> ".aqrl");
> + break;
> + case 4:
> + _amoswap_generic((volatile uint32_t *)ptr, new, ret, ".w.aqrl");
> + break;
> +#ifndef CONFIG_RISCV_32
> + case 8:
> + _amoswap_generic((volatile uint64_t *)ptr, new, ret, ".d.aqrl");
> + break;
> +#endif
> + default:
> + __bad_xchg(ptr, size), ret = 0;
> + }
I see no real reason to use a comma expression here, the more that "break"
needs adding anyway. I wonder why here you don't use ...
> +/* This function doesn't exist, so you'll get a linker error
> + if something tries to do an invalid cmpxchg(). */
> +extern unsigned long __bad_cmpxchg(volatile void *ptr, int size);
> +
> +/*
> + * Atomic compare and exchange. Compare OLD with MEM, if identical,
> + * store NEW in MEM. Return the initial value in MEM. Success is
> + * indicated by comparing RETURN with OLD.
> + */
> +static always_inline unsigned long __cmpxchg(volatile void *ptr,
> + unsigned long old,
> + unsigned long new,
> + int size)
> +{
> + unsigned long ret;
> +
> + switch ( size )
> + {
> + case 1:
> + ret = emulate_cmpxchg_1_2((volatile uint8_t *)ptr, old, new,
> + ".aq", ".aqrl");
> + break;
> + case 2:
> + ret = emulate_cmpxchg_1_2((volatile uint16_t *)ptr, old, new,
> + ".aq", ".aqrl");
> + break;
> + case 4:
> + ret = _generic_cmpxchg((volatile uint32_t *)ptr, old, new,
> + ".w.aq", ".w.aqrl");
> + break;
> +#ifndef CONFIG_32BIT
> + case 8:
> + ret = _generic_cmpxchg((volatile uint64_t *)ptr, old, new,
> + ".d.aq", ".d.aqrl");
> + break;
> +#endif
> + default:
> + return __bad_cmpxchg(ptr, size);
... the approach used here.
Also (style nit) the comment on __bad_cmpxchg() is malformed, unlike that
ahead of __bad_xchg().
Jan
