linux-kernel - [PATCH v2] memory/samsung: reduce unnecessary mutex lock area

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Date:   Tue, 12 May 2020 04:08:27 -0700
From:   Bernard Zhao <bernard@...o.com>
To:     Lukasz Luba <lukasz.luba@....com>, Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     opensource.kernel@...o.com, Bernard Zhao <bernard@...o.com>
Subject: [PATCH v2] memory/samsung: reduce unnecessary mutex lock area

Maybe dmc->df->lock seems not needed to protect "if (ret)
& dev_warn" branch. Maybe this change speed up the code a bit.

Signed-off-by: Bernard Zhao <bernard@...o.com>
----
Changes since v1:
*change release lock before the if statement.
*revert dmc->df->lock mutex lock to protect function
exynos5_dmc_perf_events_check
Link for V1:
*https://lore.kernel.org/patchwork/patch/1238888/
---
 drivers/memory/samsung/exynos5422-dmc.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/memory/samsung/exynos5422-dmc.c b/drivers/memory/samsung/exynos5422-dmc.c
index 22a43d662833..25196d6268e2 100644
--- a/drivers/memory/samsung/exynos5422-dmc.c
+++ b/drivers/memory/samsung/exynos5422-dmc.c
@@ -1346,15 +1346,13 @@ static irqreturn_t dmc_irq_thread(int irq, void *priv)
 	struct exynos5_dmc *dmc = priv;
 
 	mutex_lock(&dmc->df->lock);
-
 	exynos5_dmc_perf_events_check(dmc);
-
 	res = update_devfreq(dmc->df);
+	mutex_unlock(&dmc->df->lock);
+
 	if (res)
 		dev_warn(dmc->dev, "devfreq failed with %d\n", res);
 
-	mutex_unlock(&dmc->df->lock);
-
 	return IRQ_HANDLED;
 }
 
-- 
2.26.2