Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH] i386: Fix a couple busy loops in mach_wakecpu.h:wait_for_init_deassert() | Date | Fri, 24 Aug 2007 14:07:25 +0200 |
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On Friday 24 August 2007 13:59:32 Denys Vlasenko wrote: > 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.
I find it also non obvious. It would be really better to have a barrier or equivalent (volatile or variable clobber) in the atomic_read()
> 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.
Agreed.
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