From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753235AbaCLJV2 (ORCPT ); Wed, 12 Mar 2014 05:21:28 -0400 Received: from cantor2.suse.de ([195.135.220.15]:40945 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753018AbaCLJV1 (ORCPT ); Wed, 12 Mar 2014 05:21:27 -0400 Date: Wed, 12 Mar 2014 10:21:25 +0100 From: Jiri Bohac To: John Stultz Cc: Thomas Gleixner , Jiri Bohac , linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: is printk() safe within a timekeeper_seq write section? Message-ID: <20140312092125.GA30305@midget.suse.cz> References: <20140306174531.GA30634@midget.suse.cz> <531F6429.8050008@linaro.org> <531F8605.10003@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <531F8605.10003@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 11, 2014 at 02:54:13PM -0700, John Stultz wrote: > Ok, so a generic solution is probably not going to be worth it then. My > thought was that since we do a very limited amount of informational > printks in the timekeeping code, we can be fairly safe delaying the > print-out until we drop the locks. > > For timekeeping, its really 4 call sites: > * invalid inject_sleep_time deltas > * > 11% clocksource freq adjustments > * insert leap second > * delete leap second I believe these last two were made safe by commit ca4523cd (timekeeping: Shorten seq_count region). write_seqcount_begin(&timekeeper_seq) is now done after the accumulate_nsecs_to_secs(tk) from where the printks are called. Regards, -- Jiri Bohac SUSE Labs, SUSE CZ