linux-kernel - RE: [PATCH v5] PM / devfreq: Restart previous governor if new governor fails to start

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Date:   Tue, 12 Mar 2019 16:17:14 +0900
From:   MyungJoo Ham <myungjoo.ham@...sung.com>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        Sibi Sankar <sibis@...eaurora.org>
CC:     Kyungmin Park <kyungmin.park@...sung.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-msm-owner@...r.kernel.org" 
        <linux-arm-msm-owner@...r.kernel.org>,
        Saravana Kannan <skannan@...eaurora.org>
Subject: RE: [PATCH v5] PM / devfreq: Restart previous governor if new
 governor fails to start

>From: Saravana Kannan <skannan@...eaurora.org>
>
>If the new governor fails to start, switch back to old governor so that the
>devfreq state is not left in some weird limbo.
>
>[Mjungjoo: assume fatal on revert failure and set df->governor to NULL]
>Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
>Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
>Reviewed-by: Chanwoo Choi <cw00.choi@...sung.com>

I'll modify WARN->ERROR for the case when it's fatal:

>+		if (ret) {
>+			dev_warn(dev,
>+				 "%s: reverting to Governor %s failed (%d)\n",
>+				 __func__, df->governor_name, ret);
>+			df->governor = NULL;
>+		}

Acked-by: MyungJoo Ham <myungjoo.ham@...sung.com>


>---
>V5:
>* assume fatal on revert failure and set df->governor to NULL
>
>V4:
>* Removed prev_governor check.
>
>V3:
>* Fix NULL deref for real this time.
>* Addressed some style preferences.
>
>V2:
>* Fixed typo in commit text
>* Fixed potential NULL deref
>
> drivers/devfreq/devfreq.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>