From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754101Ab1JPK5Y (ORCPT ); Sun, 16 Oct 2011 06:57:24 -0400 Received: from mail-pz0-f42.google.com ([209.85.210.42]:64860 "EHLO mail-pz0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754027Ab1JPK5V (ORCPT ); Sun, 16 Oct 2011 06:57:21 -0400 From: Yong Zhang To: linux-kernel@vger.kernel.org Cc: linux-rt-users@vger.kernel.org, tglx@linutronix.de Subject: [RFC] [PATCH -rt 3/5] printk: don't call printk_tick in printk_needs_cpu() Date: Sun, 16 Oct 2011 18:56:45 +0800 Message-Id: <1318762607-2261-4-git-send-email-yong.zhang0@gmail.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1318762607-2261-1-git-send-email-yong.zhang0@gmail.com> References: <1318762607-2261-1-git-send-email-yong.zhang0@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org printk_tick() can't be called in atomic context, otherwise below warning will show: [ 117.597095] BUG: sleeping function called from invalid context at kernel/rtmutex.c:645 [ 117.597102] in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: kworker/0:0 [ 117.597111] Pid: 0, comm: kworker/0:0 Not tainted 3.0.6-rt17-00284-gb76d419-dirty #7 [ 117.597116] Call Trace: [ 117.597131] [] ? printk+0x1d/0x24 [ 117.597142] [] __might_sleep+0xe6/0x110 [ 117.597151] [] rt_spin_lock+0x1c/0x30 [ 117.597158] [] __wake_up+0x26/0x60 [ 117.597166] [] printk_tick+0x3e/0x40 [ 117.597173] [] printk_needs_cpu+0x24/0x30 [ 117.597181] [] tick_nohz_stop_sched_tick+0x2e8/0x410 [ 117.597191] [] ? sched_clock_idle_wakeup_event+0x1a/0x20 [ 117.597201] [] cpu_idle+0x4a/0xb0 [ 117.597209] [] start_secondary+0xd3/0xd7 Signed-off-by: Yong Zhang --- kernel/printk.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/printk.c b/kernel/printk.c index 0c9a0ab..a50af4e 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -1282,8 +1282,8 @@ void printk_tick(void) int printk_needs_cpu(int cpu) { - if (cpu_is_offline(cpu)) - printk_tick(); + if (unlikely(cpu_is_offline(cpu))) + __this_cpu_write(printk_pending, 0); return __this_cpu_read(printk_pending); } -- 1.7.1