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Message-ID: <30121.1268656565@redhat.com> Date: Mon, 15 Mar 2010 12:36:05 +0000 From: David Howells <dhowells@...hat.com> To: Stefan Richter <stefanr@...6.in-berlin.de> Cc: dhowells@...hat.com, torvalds@...l.org, akpm@...ux-foundation.org, sgruszka@...hat.com, davem@...emloft.net, linux-kernel@...r.kernel.org, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Randy Dunlap <rdunlap@...otime.net> Subject: Re: [PATCH] Document Linux's circular buffering capabilities Stefan Richter <stefanr@...6.in-berlin.de> wrote: > Would you agree to add a quick note that these examples are simple > enough to not strictly require ACCESS_ONCE but are meant to show what > more general code would have to do? Else a reader might be left puzzled > why he can't see in the example code the circumstances which require > ACCESS_ONCE and may remain unsure about where to use it in his own works... How about adding a bit: Note the use of ACCESS_ONCE() in both algorithms to read the opposition index. This prevents the compiler from discarding and reloading its cached value - -which some compilers will do across smp_read_barrier_depends(). +which some compilers will do across smp_read_barrier_depends(). This isn't +strictly needed if you can be sure that the opposition index will _only_ be +used the once. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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