Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263886AbTIICaU (ORCPT ); Mon, 8 Sep 2003 22:30:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263666AbTIICaU (ORCPT ); Mon, 8 Sep 2003 22:30:20 -0400 Received: from dp.samba.org ([66.70.73.150]:64223 "EHLO lists.samba.org") by vger.kernel.org with ESMTP id S263886AbTIICaO (ORCPT ); Mon, 8 Sep 2003 22:30:14 -0400 From: Rusty Russell To: Hugh Dickins Cc: Ulrich Drepper , Jamie Lokier , Andrew Morton , Stephen Hemminger , Linus Torvalds , Linux Kernel Subject: Re: [PATCH] Re: today's futex changes In-reply-to: Your message of "Mon, 08 Sep 2003 18:33:04 +0100." Date: Tue, 09 Sep 2003 11:37:08 +1000 Message-Id: <20030909023011.CD7122C22F@lists.samba.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1812 Lines: 46 In message you write: > Most of it (the futex_wait tweaks) looked fine to me - > though I look forward to the first report of that BUG(). Me too. But at least we'll *get* a report if someone does spurious wakeups. > Part 2, requiring VM_WRITE and removing the comment on VM_MAYSHARE, > seems a regression to me. Perhaps I misinterpreted Linus' action in > taking Jamie's patch: I took that to mean he relented a little on his > hardline position about VM_SHARED, and now accepts that in this context > VM_MAYSHARE is more appropriate (easier to document). I know I argued > that readonly futices are pointless, but I thought Jamie gave a good > picture of how a readonly view could still be used. I'd rather that > part were a separate patch, so Linus can merge or not as he wishes. Sure, I jumboed them together for feedback from you guys. All users I am currently aware of won't care either way. Current test-5 is: Sees Changes Sees FUTEX_WAKE from another MAP_SHARED from another MAP_SHARED MAP_PRIVATE read-only: Y N MAP_PRIVATE read-write: Y* N MAP_SHARED read-only: Y Y MAP_SHARED read-write: Y Y [* Only until page is written to, after which COW splits them ] Previously, the FUTEX_WAKE column was identical to the first column. Now, IMHO, this new semantic is more sensible, but I don't really mind. But I don't recall anything about believable use of RO futexes: Jamie? Cheers, Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - 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/