Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751553AbaB1DjJ (ORCPT ); Thu, 27 Feb 2014 22:39:09 -0500 Received: from smtp.codeaurora.org ([198.145.11.231]:42096 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750818AbaB1DjH (ORCPT ); Thu, 27 Feb 2014 22:39:07 -0500 From: Saravana Kannan To: MyungJoo Ham , Kyungmin Park Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "Saravana Kannan" Subject: [PATCH] PM / devfreq: Rewrite devfreq_update_status() to fix multiple bugs Date: Thu, 27 Feb 2014 19:38:57 -0800 Message-Id: <1393558737-24037-1-git-send-email-skannan@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The current devfreq_update_status() has the following bugs: - If previous frequency doesn't have a valid level, it does an out of bounds access into the trans_table and causes memory corruption. - When the new frequency doesn't have a valid level, the time spent in the new frequency is counted towards the next valid frequency switch instead of being ignored. - The time spent on the previous frequency is added to the new frequency's stats instead of the previous frequency's stats. This patch fixes all of this. Signed-off-by: Saravana Kannan --- drivers/devfreq/devfreq.c | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index a0b2f7e..2042ec3 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -91,26 +91,35 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq) */ static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq) { - int lev, prev_lev; + int lev, prev_lev, ret = 0; unsigned long cur_time; - lev = devfreq_get_freq_level(devfreq, freq); - if (lev < 0) - return lev; - cur_time = jiffies; - devfreq->time_in_state[lev] += + + prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq); + if (prev_lev < 0) { + ret = prev_lev; + goto out; + } + + devfreq->time_in_state[prev_lev] += cur_time - devfreq->last_stat_updated; - if (freq != devfreq->previous_freq) { - prev_lev = devfreq_get_freq_level(devfreq, - devfreq->previous_freq); + + lev = devfreq_get_freq_level(devfreq, freq); + if (lev < 0) { + ret = lev; + goto out; + } + + if (lev != prev_lev) { devfreq->trans_table[(prev_lev * devfreq->profile->max_state) + lev]++; devfreq->total_trans++; } - devfreq->last_stat_updated = cur_time; - return 0; +out: + devfreq->last_stat_updated = cur_time; + return ret; } /** -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation -- 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/