On Fri, Aug 17, 2007 at 03:09:57PM +1000, Paul Mackerras wrote: > Herbert Xu writes: > > > Can you find an actual atomic_read code snippet there that is > > broken without the volatile modifier? > > There are some in arch-specific code, for example line 1073 of > arch/mips/kernel/smtc.c. On mips, cpu_relax() is just barrier(), so > the empty loop body is ok provided that atomic_read actually does the > load each time around the loop.
A barrier() is all you need to force the compiler to reread the value. The people advocating volatile in this thread are talking about code that doesn't use barrier()/cpu_relax(). Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <[EMAIL PROTECTED]> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
