On Thu, Aug 16, 2007 at 02:11:43PM +1000, Paul Mackerras wrote: > > The uses of atomic_read where one might want it to allow caching of > the result seem to me to fall into 3 categories: > > 1. Places that are buggy because of a race arising from the way it's > used. > > 2. Places where there is a race but it doesn't matter because we're > doing some clever trick. > > 3. Places where there is some locking in place that eliminates any > potential race.
Agreed. > In case 1, adding volatile won't solve the race, of course, but it's > hard to argue that we shouldn't do something because it will slow down > buggy code. Case 2 is hopefully pretty rare and accompanied by large > comment blocks, and in those cases caching the result of atomic_read > explicitly in a local variable would probably make the code clearer. > And in case 3 there is no reason to use atomic_t at all; we might as > well just use an int. Since adding volatile doesn't help any of the 3 cases, and takes away optimisations from both 2 and 3, I wonder what is the point of the addition after all? 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
