Thread (3 messages) 3 messages, 3 authors, 2016-10-12

Re: [PATCH v2] PM / devfreq: Add proper locking around list_del()

From: MyungJoo Ham <myungjoo.ham@samsung.com>
Date: 2016-09-30 13:46:55
Also in: linux-samsung-soc

On Thu, Sep 29, 2016 at 11:13 AM, Axel Lin [off-list ref] wrote:
Use devfreq_list_lock around list_del() to prevent list corruption.

Signed-off-by: Axel Lin <redacted>
LGTM.

Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
quoted hunk ↗ jump to hunk
---
v2: changes base on MyungJoo's comment.
Note, devfreq_list_lock lock region does not to include device_unregister(&devfreq->dev);
 drivers/devfreq/devfreq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 478006b..66d3c718 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -594,17 +594,19 @@ struct devfreq *devfreq_add_device(struct device *dev,
        if (devfreq->governor)
                err = devfreq->governor->event_handler(devfreq,
                                        DEVFREQ_GOV_START, NULL);
-       mutex_unlock(&devfreq_list_lock);
        if (err) {
                dev_err(dev, "%s: Unable to start governor for the device\n",
                        __func__);
                goto err_init;
        }
+       mutex_unlock(&devfreq_list_lock);

        return devfreq;

 err_init:
        list_del(&devfreq->node);
+       mutex_unlock(&devfreq_list_lock);
+
        device_unregister(&devfreq->dev);
 err_out:
        return ERR_PTR(err);
--
2.7.4

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-- 
MyungJoo Ham, Ph.D.
Frontier CS Lab, S/W Center, Samsung Electronics
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