PM / devfreq: mediatek: protect oop in critical session

mtk_ccifreq_opp_notifier is reenter function when policy0 / policy6
change freq, so mutex_lock should protect all OPP event.

Link: https://lore.kernel.org/lkml/20230818021741.6173-1-chun-jen.tseng@mediatek.com/T/
Signed-off-by: Mark Tseng <chun-jen.tseng@mediatek.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

diff --git a/drivers/devfreq/mtk-cci-devfreq.c b/drivers/devfreq/mtk-cci-devfreq.c
index 83a73f0ccd803b1efec40ba2722dbed0b21d5fab..b0ed25e33f2bb2479774593e7a72fdb77cd9067b 100644 (file)
--- a/drivers/devfreq/mtk-cci-devfreq.c
+++ b/drivers/devfreq/mtk-cci-devfreq.c
@@ -137,6 +137,8 @@ static int mtk_ccifreq_target(struct device *dev, unsigned long *freq,
        if (drv->pre_freq == *freq)
                return 0;
 
+       mutex_lock(&drv->reg_lock);
+
        inter_voltage = drv->inter_voltage;
        cci_pll = clk_get_parent(drv->cci_clk);
 
@@ -147,8 +149,6 @@ static int mtk_ccifreq_target(struct device *dev, unsigned long *freq,
                return PTR_ERR(opp);
        }
 
-       mutex_lock(&drv->reg_lock);
-
        voltage = dev_pm_opp_get_voltage(opp);
        dev_pm_opp_put(opp);
 
@@ -227,9 +227,9 @@ static int mtk_ccifreq_opp_notifier(struct notifier_block *nb,
        drv = container_of(nb, struct mtk_ccifreq_drv, opp_nb);
 
        if (event == OPP_EVENT_ADJUST_VOLTAGE) {
+               mutex_lock(&drv->reg_lock);
                freq = dev_pm_opp_get_freq(opp);
 
-               mutex_lock(&drv->reg_lock);
                /* current opp item is changed */
                if (freq == drv->pre_freq) {
                        volt = dev_pm_opp_get_voltage(opp);