Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752061Ab2KJCIY (ORCPT ); Fri, 9 Nov 2012 21:08:24 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.146]:45340 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750810Ab2KJCIX (ORCPT ); Fri, 9 Nov 2012 21:08:23 -0500 Message-ID: <509DA63E.7070500@us.ibm.com> Date: Fri, 09 Nov 2012 16:56:30 -0800 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 To: Kees Cook CC: linux-kernel@vger.kernel.org, Anton Vorontsov , Colin Cross , Tony Luck , Thomas Gleixner Subject: Re: [PATCH v2] pstore/ram: no timekeeping calls when unavailable References: <20121105220059.GA6379@www.outflux.net> In-Reply-To: <20121105220059.GA6379@www.outflux.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12111000-1976-0000-0000-0000133C9A0A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1674 Lines: 48 On 11/05/2012 02:00 PM, Kees Cook wrote: > We must not call timekeeping functions unless they are available. If we dump > before they have resumed, avoid a WARN_ON by setting the timestamp to 0. > > Since the "ram" pstore driver can be a module, we must have > timekeeping_suspended exported. > > Reported-by: Doug Anderson > Cc: Anton Vorontsov > Cc: John Stultz > Signed-off-by: Kees Cook > --- > v2: > - export needed for timekeeping_suspended (thanks to Fengguang Wu). > --- > fs/pstore/ram.c | 8 +++++++- > kernel/time/timekeeping.c | 1 + > 2 files changed, 8 insertions(+), 1 deletion(-) > > diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c > index 1a4f6da..6d014e0 100644 > --- a/fs/pstore/ram.c > +++ b/fs/pstore/ram.c > @@ -171,7 +171,13 @@ static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz) > struct timeval timestamp; > size_t len; > > - do_gettimeofday(×tamp); > + /* Handle dumping before timekeeping has resumed. */ > + if (unlikely(timekeeping_suspended)) { > + timestamp.tv_sec = 0; > + timestamp.tv_usec = 0; > + } else > + do_gettimeofday(×tamp); > + Would nulling out the timestamp be better done in do_gettimeofday()? That way we don't have to export timekeeping internals and users would get something more sane for this corner case. 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/