Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751077AbaKFDqk (ORCPT ); Wed, 5 Nov 2014 22:46:40 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:39980 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750931AbaKFDqg (ORCPT ); Wed, 5 Nov 2014 22:46:36 -0500 Date: Wed, 5 Nov 2014 19:46:36 -0800 From: Greg Kroah-Hartman To: Peter Hurley Cc: Jiri Slaby , One Thousand Gnomes , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Subject: Re: [PATCH -next v2 10/26] tty: Don't take tty_mutex for tty count changes Message-ID: <20141106034636.GA26944@kroah.com> References: <1413491125-20134-1-git-send-email-peter@hurleysoftware.com> <1415207589-15967-1-git-send-email-peter@hurleysoftware.com> <1415207589-15967-11-git-send-email-peter@hurleysoftware.com> <20141106023310.GA5035@kroah.com> <545ADF52.9030401@hurleysoftware.com> <545AE1EE.30902@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <545AE1EE.30902@hurleysoftware.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 05, 2014 at 09:50:22PM -0500, Peter Hurley wrote: > On 11/05/2014 09:39 PM, Peter Hurley wrote: > > On 11/05/2014 09:33 PM, Greg Kroah-Hartman wrote: > >> On Wed, Nov 05, 2014 at 12:12:53PM -0500, Peter Hurley wrote: > >>> Holding tty_mutex is no longer required to serialize changes to > >>> the tty_count or to prevent concurrent opens of closing ttys; > >>> tty_lock() is sufficient. > >>> > >>> Reviewed-by: Alan Cox > >>> Signed-off-by: Peter Hurley > >>> --- > >>> drivers/tty/tty_io.c | 6 ------ > >>> 1 file changed, 6 deletions(-) > >>> > >>> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c > >>> index ea8c6cae8d12..e59de81c39a9 100644 > >>> --- a/drivers/tty/tty_io.c > >>> +++ b/drivers/tty/tty_io.c > >>> @@ -1804,10 +1804,6 @@ int tty_release(struct inode *inode, struct file *filp) > >>> * each iteration we avoid any problems. > >>> */ > >>> while (1) { > >>> - /* Guard against races with tty->count changes elsewhere and > >>> - opens on /dev/tty */ > >>> - > >>> - mutex_lock(&tty_mutex); > >>> tty_lock_pair(tty, o_tty); > >>> tty_closing = tty->count <= 1; > >>> o_tty_closing = o_tty && > >>> @@ -1840,7 +1836,6 @@ int tty_release(struct inode *inode, struct file *filp) > >>> printk(KERN_WARNING "%s: %s: read/write wait queue active!\n", > >>> __func__, tty_name(tty, buf)); > >>> tty_unlock_pair(tty, o_tty); > >>> - mutex_unlock(&tty_mutex); > >>> schedule(); > >>> } > >>> > >> > >> The code in my tree in this section of tty_release() looks a bit > >> different, so I had to hand-apply this patch. > > > > Although there's nothing wrong with your version, I'm wondering why this > > didn't apply cleanly. > > > > While I go look at your tree, can you check that these patches are > > sitting on top of the earlier two patches you applied to your tty-linus > > branch; specifically 'tty: Fix high cpu load if tty is unreleasable' and > > 'tty: Prevent "read/write wait queue active!" log flooding'? > > Yep, that's the problem: your 'tty-testing' branch doesn't have the 3 patches > from me that you put in your 'tty-linus' branch earlier this evening. Those are: > > serial: Fix divide-by-zero fault in uart_get_divisor() > tty: Fix high cpu load if tty is unreleasable > tty: Prevent "read/write wait queue active!" log flooding > > How can I help fix this? Ah, didn't realize that was the issue, I've merged the branches together now, so all should be good. Sorry for the noise, greg k-h -- 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/