Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756497Ab1EPXKp (ORCPT ); Mon, 16 May 2011 19:10:45 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:60020 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755870Ab1EPXKn (ORCPT ); Mon, 16 May 2011 19:10:43 -0400 Subject: Re: [PATCH 2/3] printk: Add %ptc to safely print a task's comm From: John Stultz To: Jiri Slaby Cc: LKML , "Ted Ts'o" , KOSAKI Motohiro , David Rientjes , Dave Hansen , Andrew Morton , linux-mm@kvack.org In-Reply-To: <4DD19D10.3000201@gmail.com> References: <1305580757-13175-1-git-send-email-john.stultz@linaro.org> <1305580757-13175-3-git-send-email-john.stultz@linaro.org> <4DD19D10.3000201@gmail.com> Content-Type: text/plain; charset="UTF-8" Date: Mon, 16 May 2011 16:10:32 -0700 Message-ID: <1305587432.2915.57.camel@work-vm> 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 Content-Length: 2075 Lines: 56 On Mon, 2011-05-16 at 23:54 +0200, Jiri Slaby wrote: > On 05/16/2011 11:19 PM, John Stultz wrote: > > Accessing task->comm requires proper locking. However in the past > > access to current->comm could be done without locking. This > > is no longer the case, so all comm access needs to be done > > while holding the comm_lock. > > > > In my attempt to clean up unprotected comm access, I've noticed > > most comm access is done for printk output. To simplify correct > > locking in these cases, I've introduced a new %ptc format, > > which will print the corresponding task's comm. > > > > Example use: > > printk("%ptc: unaligned epc - sending SIGBUS.\n", current); > > > > CC: Ted Ts'o > > CC: KOSAKI Motohiro > > CC: David Rientjes > > CC: Dave Hansen > > CC: Andrew Morton > > CC: linux-mm@kvack.org > > Signed-off-by: John Stultz > > --- > > lib/vsprintf.c | 24 ++++++++++++++++++++++++ > > 1 files changed, 24 insertions(+), 0 deletions(-) > > > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > > index bc0ac6b..b7a9953 100644 > > --- a/lib/vsprintf.c > > +++ b/lib/vsprintf.c > > @@ -797,6 +797,23 @@ char *uuid_string(char *buf, char *end, const u8 *addr, > > return string(buf, end, uuid, spec); > > } > > > > +static noinline_for_stack > > Actually, why noinline? Did your previous version have there some > TASK_COMM_LEN buffer or anything on stack which is not there anymore? No, I was just following how almost all of the pointer() called functions were declared. But with two pointers and a long, I add more then ip6_string() has on the stack, which uses the same notation. But I can drop that bit if there's really no need for it. thanks -john -- 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/