Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964953Ab3HIP0E (ORCPT ); Fri, 9 Aug 2013 11:26:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57596 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934350Ab3HIP0C (ORCPT ); Fri, 9 Aug 2013 11:26:02 -0400 Date: Fri, 9 Aug 2013 17:19:13 +0200 From: Oleg Nesterov To: Linus Torvalds , Christine Caulfield , David Teigland Cc: Long Gao , Al Viro , Andrew Morton , Linux Kernel Mailing List Subject: [PATCH 1/1] dlm: kill the unnecessary and wrong device_close()->recalc_sigpending() Message-ID: <20130809151913.GB4619@redhat.com> References: <20130808191749.GA12062@redhat.com> <20130809151852.GA4619@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130809151852.GA4619@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1693 Lines: 53 device_close()->recalc_sigpending() is not needed, sigprocmask() takes care of TIF_SIGPENDING correctly. And without ->siglock it is racy and wrong, it can wrongly clear TIF_SIGPENDING and miss a signal. But even with this patch device_close() is still buggy: 1. sigprocmask() should not be used, we have set_task_blocked(), but this is minor. 2. We should never block SIGKILL or SIGSTOP, and this is what the code tries to do. 3. This can't protect against SIGKILL or SIGSTOP anyway. Another thread can do signal_wake_up(), say, do_signal_stop() or complete_signal() or debugger. 4. sigprocmask(SIG_BLOCK, allsigs) doesn't necessarily clears TIF_SIGPENDING, say, freezing() or ->jobctl. 5. device_write() looks equally wrong by the same reason. Looks like, this tries to protect some wait_event_interruptible() logic from signals, it should be turned into uninterruptible wait. Or we need to implement something like signals_stop/start for such a use-case. Signed-off-by: Oleg Nesterov --- fs/dlm/user.c | 1 - 1 files changed, 0 insertions(+), 1 deletions(-) diff --git a/fs/dlm/user.c b/fs/dlm/user.c index 911649a..8121491 100644 --- a/fs/dlm/user.c +++ b/fs/dlm/user.c @@ -686,7 +686,6 @@ static int device_close(struct inode *inode, struct file *file) device_remove_lockspace() */ sigprocmask(SIG_SETMASK, &tmpsig, NULL); - recalc_sigpending(); return 0; } -- 1.5.5.1 -- 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/