On Tue, 14 Aug 2007, Christoph Lameter wrote:
> On Thu, 9 Aug 2007, Chris Snook wrote: > > > This patchset makes the behavior of atomic_read uniform by removing the > > volatile keyword from all atomic_t and atomic64_t definitions that currently > > have it, and instead explicitly casts the variable as volatile in > > atomic_read(). This leaves little room for creative optimization by the > > compiler, and is in keeping with the principles behind "volatile considered > > harmful". > > volatile is generally harmful even in atomic_read(). Barriers control > visibility and AFAICT things are fine. Frankly, I don't see the need for this series myself either. Personal opinion (others may differ), but I consider "volatile" to be a sad / unfortunate wart in C (numerous threads on this list and on the gcc lists/bugzilla over the years stand testimony to this) and if we _can_ steer clear of it, then why not -- why use this ill-defined primitive whose implementation has often differed over compiler versions and platforms? Granted, barrier() _is_ heavy-handed in that it makes the optimizer forget _everything_, but then somebody did post a forget() macro on this thread itself ... [ BTW, why do we want the compiler to not optimize atomic_read()'s in the first place? Atomic ops guarantee atomicity, which has nothing to do with "volatility" -- users that expect "volatility" from atomic ops are the ones who must be fixed instead, IMHO. ] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
