From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id AA7076B0022 for ; Mon, 16 May 2011 19:10:43 -0400 (EDT) Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by e35.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id p4GMrbGZ017760 for ; Mon, 16 May 2011 16:53:37 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p4GNAbhU158004 for ; Mon, 16 May 2011 17:10:37 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p4GHAAWq017306 for ; Mon, 16 May 2011 11:10:10 -0600 Subject: Re: [PATCH 2/3] printk: Add %ptc to safely print a task's comm From: John Stultz 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 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Jiri Slaby Cc: LKML , Ted Ts'o , KOSAKI Motohiro , David Rientjes , Dave Hansen , Andrew Morton , linux-mm@kvack.org 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org