From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755217Ab1HYSQ2 (ORCPT ); Thu, 25 Aug 2011 14:16:28 -0400 Received: from wondertoys-mx.wondertoys.net ([206.117.179.246]:32785 "EHLO labridge.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753707Ab1HYSQ1 (ORCPT ); Thu, 25 Aug 2011 14:16:27 -0400 Subject: Re: [PATCH 068/118] drbd: conn_printk() a dev_printk() alike for drbd's connections From: Joe Perches To: Philipp Reisner Cc: linux-kernel@vger.kernel.org, Jens Axboe , drbd-dev@lists.linbit.com In-Reply-To: <1314284934-17999-69-git-send-email-philipp.reisner@linbit.com> References: <1314284934-17999-1-git-send-email-philipp.reisner@linbit.com> <1314284934-17999-69-git-send-email-philipp.reisner@linbit.com> Content-Type: text/plain; charset="UTF-8" Date: Thu, 25 Aug 2011 11:16:25 -0700 Message-ID: <1314296185.15882.75.camel@Joe-Laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-08-25 at 17:08 +0200, Philipp Reisner wrote: > Signed-off-by: Philipp Reisner > Signed-off-by: Lars Ellenberg > --- > drivers/block/drbd/drbd_int.h | 9 +++++++++ > drivers/block/drbd/drbd_main.c | 16 +++++++++++++++- > 2 files changed, 24 insertions(+), 1 deletions(-) Couple of issues with this patch. > diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h [] > @@ -102,6 +102,15 @@ struct drbd_tconn; [] > +extern void conn_printk(const char *level, struct drbd_tconn *tconn, const char *fmt, ...); This should be extern __attribute__((format (printf, 3, 4))) void conn_printk(const char *level, struct drbd_tconn *tconn, const char *fmt, ...); to have gcc validate the printf format and arguments. > diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c [] > @@ -170,6 +170,18 @@ int _get_ldev_if_state(struct drbd_conf *mdev, enum drbd_disk_state mins) > > #endif > > +/* printk functions for connections > + */ > +void conn_printk(const char *level, struct drbd_tconn *tconn, const char *fmt, ...) > +{ > + va_list args; > + > + printk("%sd-con %s: ", level, tconn->name); > + va_start(args, fmt); > + vprintk(fmt, args); > + va_end(args); And using printk then vprintk is susceptible to another thread interleaving a different message between the printk and the vprintk. Using struct va_format and %pV is better because no message interleaving is possible. ie: void conn_printk(const char *level, struct drbd_tconn *tconn, const char *fmt, ...) { struct va_format vaf; va_list args; va_start(args, fmt); vaf.fmt = fmt; vaf.va = &args; printk("%sd-con %s: %pV", level, tconn->name, &vaf); va_end(args); }