From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753936Ab2LEOKT (ORCPT ); Wed, 5 Dec 2012 09:10:19 -0500 Received: from gibson.whatever-company.com ([87.98.251.113]:37851 "EHLO gibson.whatever-company.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752496Ab2LEOKS (ORCPT ); Wed, 5 Dec 2012 09:10:18 -0500 X-Greylist: delayed 444 seconds by postgrey-1.27 at vger.kernel.org; Wed, 05 Dec 2012 09:10:18 EST From: Sylvain Munaut To: linux-kernel@vger.kernel.org Cc: Sylvain Munaut Subject: [RFC] printk: Fix print_time length computation when no buffer is given Date: Wed, 5 Dec 2012 15:02:47 +0100 Message-Id: <1354716167-438-1-git-send-email-s.munaut@whatever-company.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The "%5lu" part of the sprintf only guarantees a minimum length, not a maximum one. This patch should make it correct for any possible timestamp. Signed-off-by: Sylvain Munaut --- kernel/printk.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/printk.c b/kernel/printk.c index 66a2ea3..2ceceea 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -847,8 +847,17 @@ static size_t print_time(u64 ts, char *buf) if (!printk_time) return 0; - if (!buf) - return 15; + if (!buf) { + size_t len = 15; + u64 ts_limit = (u64)100000 * (u64)1000000000; + + while ((ts > ts_limit) && (len < 21)) { + len++; + ts_limit = 10 * ts_limit; + } + + return len; + } rem_nsec = do_div(ts, 1000000000); return sprintf(buf, "[%5lu.%06lu] ", -- 1.7.10.4