From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1IxSDF-0001Q7-JM for user-mode-linux-devel@lists.sourceforge.net; Wed, 28 Nov 2007 11:04:45 -0800 Received: from saraswathi.solana.com ([198.99.130.12]) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1IxSDC-000059-Uh for user-mode-linux-devel@lists.sourceforge.net; Wed, 28 Nov 2007 11:04:45 -0800 Date: Wed, 28 Nov 2007 14:04:40 -0500 From: Jeff Dike Message-ID: <20071128190440.GA8313@c2.user-mode-linux.org> Mime-Version: 1.0 Content-Disposition: inline Subject: [uml-devel] [PATCH 4/4] UML - Work around host tcsetattr bug List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: user-mode-linux-devel-bounces@lists.sourceforge.net Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: Andrew Morton Cc: LKML , uml-devel Under the conditions that UML uses it, tcgetattr is guaranteed to return -EINTR when the console is attached to /dev/ptmx, making generic_console_write hang because it loops, calling tcgetattr until it succeeds. This is a host bug - see http://marc.info/?l=linux-kernel&m=119618990807182&w=2 for the details. This patch works around it by blocking SIGIO while the terminal attributes are being fiddled. Signed-off-by: Jeff Dike --- arch/um/drivers/chan_user.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) Index: linux-2.6.22/arch/um/drivers/chan_user.c =================================================================== --- linux-2.6.22.orig/arch/um/drivers/chan_user.c 2007-11-21 11:43:50.000000000 -0500 +++ linux-2.6.22/arch/um/drivers/chan_user.c 2007-11-27 14:03:10.000000000 -0500 @@ -74,10 +74,16 @@ void generic_free(void *data) int generic_console_write(int fd, const char *buf, int n) { + sigset_t old, no_sigio; struct termios save, new; int err; if (isatty(fd)) { + sigemptyset(&no_sigio); + sigaddset(&no_sigio, SIGIO); + if (sigprocmask(SIG_BLOCK, &no_sigio, &old)) + goto error; + CATCH_EINTR(err = tcgetattr(fd, &save)); if (err) goto error; @@ -97,8 +103,11 @@ int generic_console_write(int fd, const * Restore raw mode, in any case; we *must* ignore any error apart * EINTR, except for debug. */ - if (isatty(fd)) + if (isatty(fd)) { CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save)); + sigprocmask(SIG_SETMASK, &old, NULL); + } + return err; error: return -errno; ------------------------------------------------------------------------- SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. 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Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759258AbXK1TGY (ORCPT ); Wed, 28 Nov 2007 14:06:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755989AbXK1TFj (ORCPT ); Wed, 28 Nov 2007 14:05:39 -0500 Received: from saraswathi.solana.com ([198.99.130.12]:42877 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759444AbXK1TFh (ORCPT ); Wed, 28 Nov 2007 14:05:37 -0500 Date: Wed, 28 Nov 2007 14:04:40 -0500 From: Jeff Dike To: Andrew Morton Cc: LKML , uml-devel Subject: [PATCH 4/4] UML - Work around host tcsetattr bug Message-ID: <20071128190440.GA8313@c2.user-mode-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Under the conditions that UML uses it, tcgetattr is guaranteed to return -EINTR when the console is attached to /dev/ptmx, making generic_console_write hang because it loops, calling tcgetattr until it succeeds. This is a host bug - see http://marc.info/?l=linux-kernel&m=119618990807182&w=2 for the details. This patch works around it by blocking SIGIO while the terminal attributes are being fiddled. Signed-off-by: Jeff Dike --- arch/um/drivers/chan_user.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) Index: linux-2.6.22/arch/um/drivers/chan_user.c =================================================================== --- linux-2.6.22.orig/arch/um/drivers/chan_user.c 2007-11-21 11:43:50.000000000 -0500 +++ linux-2.6.22/arch/um/drivers/chan_user.c 2007-11-27 14:03:10.000000000 -0500 @@ -74,10 +74,16 @@ void generic_free(void *data) int generic_console_write(int fd, const char *buf, int n) { + sigset_t old, no_sigio; struct termios save, new; int err; if (isatty(fd)) { + sigemptyset(&no_sigio); + sigaddset(&no_sigio, SIGIO); + if (sigprocmask(SIG_BLOCK, &no_sigio, &old)) + goto error; + CATCH_EINTR(err = tcgetattr(fd, &save)); if (err) goto error; @@ -97,8 +103,11 @@ int generic_console_write(int fd, const * Restore raw mode, in any case; we *must* ignore any error apart * EINTR, except for debug. */ - if (isatty(fd)) + if (isatty(fd)) { CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save)); + sigprocmask(SIG_SETMASK, &old, NULL); + } + return err; error: return -errno;