linux-kernel - [PATCH] hwmon: (gsc-hwmon) Switch to flexible array to simplify code

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Date:   Sun, 20 Nov 2022 10:34:41 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Tim Harvey <tharvey@...eworks.com>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-hwmon@...r.kernel.org
Subject: [PATCH] hwmon: (gsc-hwmon) Switch to flexible array to simplify code

Using flexible array is more straight forward. It
  - saves 1 pointer in the 'gsc_hwmon_platform_data' structure
  - saves an indirection when using this array
  - saves some LoC and avoids some always spurious pointer arithmetic

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Compile tested only
---
 drivers/hwmon/gsc-hwmon.c               | 6 ++----
 include/linux/platform_data/gsc_hwmon.h | 5 ++---
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/hwmon/gsc-hwmon.c b/drivers/hwmon/gsc-hwmon.c
index b60ec95b5edb..73e5d92b200b 100644
--- a/drivers/hwmon/gsc-hwmon.c
+++ b/drivers/hwmon/gsc-hwmon.c
@@ -257,13 +257,10 @@ gsc_hwmon_get_devtree_pdata(struct device *dev)
 	if (nchannels == 0)
 		return ERR_PTR(-ENODEV);
 
-	pdata = devm_kzalloc(dev,
-			     sizeof(*pdata) + nchannels * sizeof(*ch),
+	pdata = devm_kzalloc(dev, struct_size(pdata, channels, nchannels),
 			     GFP_KERNEL);
 	if (!pdata)
 		return ERR_PTR(-ENOMEM);
-	ch = (struct gsc_hwmon_channel *)(pdata + 1);
-	pdata->channels = ch;
 	pdata->nchannels = nchannels;
 
 	/* fan controller base address */
@@ -277,6 +274,7 @@ gsc_hwmon_get_devtree_pdata(struct device *dev)
 
 	of_node_put(fan);
 
+	ch = pdata->channels;
 	/* allocate structures for channels and count instances of each type */
 	device_for_each_child_node(dev, child) {
 		if (fwnode_property_read_string(child, "label", &ch->name)) {
diff --git a/include/linux/platform_data/gsc_hwmon.h b/include/linux/platform_data/gsc_hwmon.h
index 281f499eda97..f2781aa7eff8 100644
--- a/include/linux/platform_data/gsc_hwmon.h
+++ b/include/linux/platform_data/gsc_hwmon.h
@@ -29,18 +29,17 @@ struct gsc_hwmon_channel {
 
 /**
  * struct gsc_hwmon_platform_data - platform data for gsc_hwmon driver
- * @channels:	pointer to array of gsc_hwmon_channel structures
- *		describing channels
  * @nchannels:	number of elements in @channels array
  * @vreference: voltage reference (mV)
  * @resolution: ADC bit resolution
  * @fan_base: register base for FAN controller
+ * @channels:	array of gsc_hwmon_channel structures describing channels
  */
 struct gsc_hwmon_platform_data {
-	const struct gsc_hwmon_channel *channels;
 	int nchannels;
 	unsigned int resolution;
 	unsigned int vreference;
 	unsigned int fan_base;
+	struct gsc_hwmon_channel channels[];
 };
 #endif
-- 
2.34.1