Re: [PATCH] i386: Fix a couple busy loops in mach_wakecpu.h:wait_for_init_deassert()

[Denys Vlasenko]

On Thursday 16 August 2007 01:39, Satyam Sharma wrote:
>
>  static inline void wait_for_init_deassert(atomic_t *deassert)
>  {
> -	while (!atomic_read(deassert));
> +	while (!atomic_read(deassert))
> +		cpu_relax();
>  	return;
>  }

For less-than-briliant people like me, it's totally non-obvious that
cpu_relax() is needed for correctness here, not just to make P4 happy.

IOW: "atomic_read" name quite unambiguously means "I will read
this variable from main memory". Which is not true and creates
potential for confusion and bugs.
--
vda
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/