Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755389Ab3IYM0B (ORCPT ); Wed, 25 Sep 2013 08:26:01 -0400 Received: from smtp1.uu.se ([130.238.7.54]:52463 "EHLO smtp1.uu.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752428Ab3IYM0A (ORCPT ); Wed, 25 Sep 2013 08:26:00 -0400 X-Greylist: delayed 440 seconds by postgrey-1.27 at vger.kernel.org; Wed, 25 Sep 2013 08:25:59 EDT MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <21058.54396.663197.35823@pilspetsen.it.uu.se> Date: Wed, 25 Sep 2013 14:18:04 +0200 From: Mikael Pettersson To: Peter Hurley CC: linux-kernel@vger.kernel.org Subject: [REGRESSION][BISECTED] 3.12-rc "n_tty: Don't wait for buffer work in read() loop" patch breaks gcc's testsuite X-Mailer: VM 7.17 under Emacs 20.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2500 Lines: 71 With 3.12-rc[12] I see unexpected failures in gcc's Ada acats testsuite, e.g. === acats tests === FAIL: a83009b FAIL: c37209a FAIL: c45531e FAIL: c45614a FAIL: c67005d FAIL: c730a01 FAIL: c74302b FAIL: cc3004a FAIL: cd2a24j FAIL: cd2a53a FAIL: cxa3001 FAIL: cxf3a07 FAIL: cxf3a08 === acats Summary === # of expected passes 2307 # of unexpected failures 13 Native configuration is x86_64-unknown-linux-gnu The exact failures vary from run to run, but some failures always occur on my x86_64 machines, and all three open gcc branches (trunk, 4.8, 4.7) are affected. With a 3.11 kernel the acats testsuite is always clean. A bisection identified: >From f95499c3030fe1bfad57745f2db1959c5b43dca8 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Sat, 15 Jun 2013 13:14:29 +0000 Subject: n_tty: Don't wait for buffer work in read() loop User-space read() can run concurrently with receiving from device; waiting for receive_buf() to complete is not required. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index fe1c399..a6eea30 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -1724,7 +1724,6 @@ static inline int input_available_p(struct tty_struct *tty, int amt) { struct n_tty_data *ldata = tty->disc_data; - tty_flush_to_ldisc(tty); if (ldata->icanon && !L_EXTPROC(tty)) { if (ldata->canon_head != ldata->read_tail) return 1; as the culprit. Reverting that from 3.12-rc2 eliminates the acats failures and brings the gcc testsuite results to what one gets with 3.11. I can't pretend to understand exactly what goes wrong, suffice it to say that the gcc testsuite harness uses a combination of shell, expect, and tcl. I suspect ptys are also involved. To repeat, bootstrap a recent gcc 4.8 snapshot w/ ada in --enable-languages, then run the test suite with "make -j6 -k check; make mail-report.log". (Adjust -jN as appropriate, but -j6 is what I'm using on my quad-core i7s.) Please consider reverting or fixing this patch. /Mikael -- 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/