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

From: Denys Vlasenko <[email-masked]>
Date: Fri, 24 Aug 2007 12:59:32 +0100

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