Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933196Ab2KFAsK (ORCPT ); Mon, 5 Nov 2012 19:48:10 -0500 Received: from mail-vc0-f202.google.com ([209.85.220.202]:53894 "EHLO mail-vc0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932295Ab2KFAsH (ORCPT ); Mon, 5 Nov 2012 19:48:07 -0500 From: David Sharp To: linux-kernel@vger.kernel.org Cc: David Sharp , Steven Rostedt , Masami Hiramatsu Subject: [PATCH v8 2/5] tracing: Reset ring buffer when changing trace_clocks Date: Mon, 5 Nov 2012 16:47:48 -0800 Message-Id: <1352162868-11347-1-git-send-email-dhsharp@google.com> X-Mailer: git-send-email 1.7.7.3 In-Reply-To: <1351864814.4004.133.camel@gandalf.local.home> References: <1351864814.4004.133.camel@gandalf.local.home> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1373 Lines: 41 Because the "tsc" clock isn't in nanoseconds, the ring buffer must be reset when changing clocks so that incomparable timestamps don't end up in the same trace. Tested: Confirmed switching clocks resets the trace buffer. Google-Bug-Id: 6980623 Signed-off-by: David Sharp Cc: Steven Rostedt Cc: Masami Hiramatsu --- kernel/trace/trace.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 9aed7f5..84aa489 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4017,6 +4017,14 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf, if (max_tr.buffer) ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func); + /* + * New clock may not be consistent with the previous clock. + * Reset the buffer so that it doesn't have incomparable timestamps. + */ + tracing_reset_online_cpus(&global_trace); + if (max_tr.buffer) + tracing_reset_online_cpus(&max_tr); + mutex_unlock(&trace_types_lock); *fpos += cnt; -- 1.7.7.3 -- 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/