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From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     Stuart Yoder <stuyoder@gmail.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
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        Bjorn Helgaas <bhelgaas@google.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Vineeth Vijayan <vneethv@linux.ibm.com>,
        Peter Oberparleiter <oberpar@linux.ibm.com>,
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        Sven Schnelle <svens@linux.ibm.com>,
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        virtualization@lists.linux-foundation.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Subject: [PATCH v6 06/12] s390/cio: Use driver_set_override() instead of open-coding
Date:   Sun,  3 Apr 2022 20:37:52 +0200
Message-Id: <20220403183758.192236-7-krzysztof.kozlowski@linaro.org>
In-Reply-To: <20220403183758.192236-1-krzysztof.kozlowski@linaro.org>
References: <20220403183758.192236-1-krzysztof.kozlowski@linaro.org>
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Use a helper to set driver_override to the reduce amount of duplicated
code.  Make the driver_override field const char, because it is not
modified by the core and it matches other subsystems.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Vineeth Vijayan <vneethv@linux.ibm.com>
---
 drivers/s390/cio/cio.h |  6 +++++-
 drivers/s390/cio/css.c | 28 ++++------------------------
 2 files changed, 9 insertions(+), 25 deletions(-)

diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 1cb9daf9c645..fa8df50bb49e 100644
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -103,7 +103,11 @@ struct subchannel {
 	struct work_struct todo_work;
 	struct schib_config config;
 	u64 dma_mask;
-	char *driver_override; /* Driver name to force a match */
+	/*
+	 * Driver name to force a match.  Do not set directly, because core
+	 * frees it.  Use driver_set_override() to set or clear it.
+	 */
+	const char *driver_override;
 } __attribute__ ((aligned(8)));
 
 DECLARE_PER_CPU_ALIGNED(struct irb, cio_irb);
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index fa8293335077..913b6ddd040b 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -338,31 +338,11 @@ static ssize_t driver_override_store(struct device *dev,
 				     const char *buf, size_t count)
 {
 	struct subchannel *sch = to_subchannel(dev);
-	char *driver_override, *old, *cp;
-
-	/* We need to keep extra room for a newline */
-	if (count >= (PAGE_SIZE - 1))
-		return -EINVAL;
-
-	driver_override = kstrndup(buf, count, GFP_KERNEL);
-	if (!driver_override)
-		return -ENOMEM;
-
-	cp = strchr(driver_override, '\n');
-	if (cp)
-		*cp = '\0';
-
-	device_lock(dev);
-	old = sch->driver_override;
-	if (strlen(driver_override)) {
-		sch->driver_override = driver_override;
-	} else {
-		kfree(driver_override);
-		sch->driver_override = NULL;
-	}
-	device_unlock(dev);
+	int ret;
 
-	kfree(old);
+	ret = driver_set_override(dev, &sch->driver_override, buf, count);
+	if (ret)
+		return ret;
 
 	return count;
 }
-- 
2.32.0