Messages in this thread |  | | | Date | Tue, 31 Oct 2006 17:23:12 -0800 | | From | Andrew Morton <> | | Subject | Re: [patch 1/1] schedule removal of FUTEX_FD |
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On Wed, 01 Nov 2006 12:19:05 +1100 Rusty Russell <rusty@rustcorp.com.au> wrote:
> On Tue, 2006-10-31 at 15:09 -0800, akpm@osdl.org wrote: > > From: Andrew Morton <akpm@osdl.org> > > > > Apparently FUTEX_FD is unfixably racy and nothing uses it (or if it does, it > > shouldn't). > > > > Add a warning printk, give any remaining users six months to migrate off it. > > This makes sense. FUTEX_FD was for the NGPT project which did userspace > threading, and hence couldn't block. It was always kind of a hack > (although unfixably racy isn't quite right, it depends on usage). > > However, the existence of FUTEX_FD is what made Ingo complain that we > couldn't simply pin the futex page in memory, because now a process > could pin one page per fd. Removing it would seem to indicate that we > can return to a much simpler scheme of (1) pinning a page when someone > does futex_wait, and (2) simply comparing futexes by physical address. > > Now, I realize with some dismay that simplicity is no longer a futex > feature, but it might be worth considering?
Sure. Perhaps we could accelerate the removal schedule if we want to do this. Let's see how many 2.6.19 users squeak first.
> Cheers, > Rusty. > PS. I used to have a patch for "ratelim_printk()" which hashed on the > format string to reduce the chance that one message limit would clobber > other messages. I'll dig it out...
I think the caller-provided-state thing will work OK? - 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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