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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? 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... - 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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