Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261236AbUCCWqy (ORCPT ); Wed, 3 Mar 2004 17:46:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261240AbUCCWqy (ORCPT ); Wed, 3 Mar 2004 17:46:54 -0500 Received: from fw.osdl.org ([65.172.181.6]:45244 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261236AbUCCWqw (ORCPT ); Wed, 3 Mar 2004 17:46:52 -0500 Date: Wed, 3 Mar 2004 14:52:54 -0800 (PST) From: Linus Torvalds To: "Richard B. Johnson" cc: David Dillow , Bill Davidsen , Roland Dreier , Linux Kernel Mailing List Subject: Re: poll() in 2.6 and beyond In-Reply-To: Message-ID: References: <1vmPm-4lU-11@gated-at.bofh.it> <1vonq-6dr-37@gated-at.bofh.it> <1voGY-6vC-41@gated-at.bofh.it> <1vpjt-7dl-17@gated-at.bofh.it> <1vpCV-7wY-41@gated-at.bofh.it> <1vpWa-7Py-19@gated-at.bofh.it> <4045106D.8060902@tmr.com> <1078286221.4302.23.camel@ori.thedillows.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1115 Lines: 28 On Wed, 3 Mar 2004, Linus Torvalds wrote: > > You should clear the "events pending" flag only when you literally remove > the event (ie at "read()" time, not at "poll()" time). Because the > select() code _will_ call down to the "poll()" functions multiple times if > it gets woken up for any bogus reason. Hmm.. The above is all still true and your poll() implementation is bad, but looking at your test program, the problematic case really shouldn't trigger (we should call poll() multiple times only when it returns zero). To trigger that bug, you'd have to occasionally call poll() with the POLLIN bit clear in the incoming events, which your test program doesn't ever do. Anyway, you should move the clearing to read(), but there may well be something else going on too. What's the frequency you are programming the thing to send interrupts at? Linus - 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/