linux-kernel - [PATCH] memory: samsung: exynos5422-dmc: Additional locking for 'curr

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Message-Id: <20200811101633.3845-1-lukasz.luba@arm.com>
Date:   Tue, 11 Aug 2020 11:16:33 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        krzk@...nel.org
Cc:     kgene@...nel.org, b.zolnierkie@...sung.com, lukasz.luba@....com
Subject: [PATCH] memory: samsung: exynos5422-dmc: Additional locking for 'curr_rate'

The 'curr_rate' is protected by local 'dmc->lock' in various places, but
not in a function exynos5_dmc_get_status(). The lock protects frequency
(and voltage) change process and the corresponding value stored in
'curr_rate'. Add the locking mechanism to protect the 'curr_rate' reading
also in the exynos5_dmc_get_status().

Suggested-by: Krzysztof Kozlowski <krzk@...nel.org>
Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 drivers/memory/samsung/exynos5422-dmc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/memory/samsung/exynos5422-dmc.c b/drivers/memory/samsung/exynos5422-dmc.c
index b9c7956e5031..952bc61e68f4 100644
--- a/drivers/memory/samsung/exynos5422-dmc.c
+++ b/drivers/memory/samsung/exynos5422-dmc.c
@@ -908,7 +908,10 @@ static int exynos5_dmc_get_status(struct device *dev,
 	int ret;
 
 	if (dmc->in_irq_mode) {
+		mutex_lock(&dmc->lock);
 		stat->current_frequency = dmc->curr_rate;
+		mutex_unlock(&dmc->lock);
+
 		stat->busy_time = dmc->load;
 		stat->total_time = dmc->total;
 	} else {
-- 
2.17.1