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Chris Friesen wrote: > Chris Snook wrote: > >> This is not a problem, since indirect references will cause the CPU to >> fetch the data from memory/cache anyway. > > Isn't Zan's sample code (that shows the problem) already using indirect > references? Yeah, I misinterpreted his conclusion. I thought about this for a while, and realized that it's perfectly legal for the compiler to re-use a value obtained from atomic_read. All that matters is that the read itself was atomic. The use (or non-use) of the volatile keyword is really more relevant to the other atomic operations. If you want to guarantee a re-read from memory, use barrier(). This, incidentally, uses volatile under the hood. -- Chris - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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