driver-core: constify data for class_find_device()

All in-kernel users of class_find_device() don't really need mutable
data for match callback.

In two places (kernel/power/suspend_test.c, drivers/scsi/osd/osd_uld.c)
this patch changes match callbacks to use const search data.

The const is propagated to rtc_class_open() and power_supply_get_by_name()
parameters.

Note that there's a dev reference leak in suspend_test.c that's not
touched in this patch.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/class.c

@@ -420,8 +420,8 @@ EXPORT_SYMBOL_GPL(class_for_each_device);
  * code.  There's no locking restriction.
  */
 struct device *class_find_device(struct class *class, struct device *start,
-				 void *data,
-				 int (*match)(struct device *, void *))
+				 const void *data,
+				 int (*match)(struct device *, const void *))
 {
 	struct class_dev_iter iter;
 	struct device *dev;

drivers/base/core.c

@@ -1617,9 +1617,9 @@ struct device *device_create(struct class *class, struct device *parent,
 }
 EXPORT_SYMBOL_GPL(device_create);
 
-static int __match_devt(struct device *dev, void *data)
+static int __match_devt(struct device *dev, const void *data)
 {
-	dev_t *devt = data;
+	const dev_t *devt = data;
 
 	return dev->devt == *devt;
 }

drivers/gpio/gpiolib.c

@@ -806,7 +806,7 @@ fail_unlock:
 }
 EXPORT_SYMBOL_GPL(gpio_export);
 
-static int match_export(struct device *dev, void *data)
+static int match_export(struct device *dev, const void *data)
 {
 	return dev_get_drvdata(dev) == data;
 }

drivers/isdn/mISDN/core.c

@@ -168,13 +168,13 @@ static struct class mISDN_class = {
 };
 
 static int
-_get_mdevice(struct device *dev, void *id)
+_get_mdevice(struct device *dev, const void *id)
 {
 	struct mISDNdevice *mdev = dev_to_mISDN(dev);
 
 	if (!mdev)
 		return 0;
-	if (mdev->id != *(u_int *)id)
+	if (mdev->id != *(const u_int *)id)
 		return 0;
 	return 1;
 }

drivers/net/phy/mdio_bus.c

@@ -95,7 +95,7 @@ static struct class mdio_bus_class = {
 
 #if IS_ENABLED(CONFIG_OF_MDIO)
 /* Helper function for of_mdio_find_bus */
-static int of_mdio_bus_match(struct device *dev, void *mdio_bus_np)
+static int of_mdio_bus_match(struct device *dev, const void *mdio_bus_np)
 {
 	return dev->of_node == mdio_bus_np;
 }

drivers/power/power_supply_core.c

@@ -141,7 +141,7 @@ int power_supply_set_battery_charged(struct power_supply *psy)
 }
 EXPORT_SYMBOL_GPL(power_supply_set_battery_charged);
 
-static int power_supply_match_device_by_name(struct device *dev, void *data)
+static int power_supply_match_device_by_name(struct device *dev, const void *data)
 {
 	const char *name = data;
 	struct power_supply *psy = dev_get_drvdata(dev);
@@ -149,7 +149,7 @@ static int power_supply_match_device_by_name(struct device *dev, void *data)
 	return strcmp(psy->name, name) == 0;
 }
 
-struct power_supply *power_supply_get_by_name(char *name)
+struct power_supply *power_supply_get_by_name(const char *name)
 {
 	struct device *dev = class_find_device(power_supply_class, NULL, name,
 					power_supply_match_device_by_name);

drivers/rtc/interface.c

@@ -587,16 +587,16 @@ void rtc_update_irq(struct rtc_device *rtc,
 }
 EXPORT_SYMBOL_GPL(rtc_update_irq);
 
-static int __rtc_match(struct device *dev, void *data)
+static int __rtc_match(struct device *dev, const void *data)
 {
-	char *name = (char *)data;
+	const char *name = data;
 
 	if (strcmp(dev_name(dev), name) == 0)
 		return 1;
 	return 0;
 }
 
-struct rtc_device *rtc_class_open(char *name)
+struct rtc_device *rtc_class_open(const char *name)
 {
 	struct device *dev;
 	struct rtc_device *rtc = NULL;

drivers/scsi/hosts.c

@@ -468,10 +468,10 @@ void scsi_unregister(struct Scsi_Host *shost)
 }
 EXPORT_SYMBOL(scsi_unregister);
 
-static int __scsi_host_match(struct device *dev, void *data)
+static int __scsi_host_match(struct device *dev, const void *data)
 {
 	struct Scsi_Host *p;
-	unsigned short *hostnum = (unsigned short *)data;
+	const unsigned short *hostnum = data;
 
 	p = class_to_shost(dev);
 	return p->host_no == *hostnum;

drivers/scsi/osd/osd_uld.c

@@ -268,18 +268,11 @@ static inline bool _the_same_or_null(const u8 *a1, unsigned a1_len,
 	return 0 == memcmp(a1, a2, a1_len);
 }
 
-struct find_oud_t {
-	const struct osd_dev_info *odi;
-	struct device *dev;
-	struct osd_uld_device *oud;
-} ;
-
-int _mach_odi(struct device *dev, void *find_data)
+static int _match_odi(struct device *dev, const void *find_data)
 {
 	struct osd_uld_device *oud = container_of(dev, struct osd_uld_device,
 						  class_dev);
-	struct find_oud_t *fot = find_data;
-	const struct osd_dev_info *odi = fot->odi;
+	const struct osd_dev_info *odi = find_data;
 
 	if (_the_same_or_null(oud->odi.systemid, oud->odi.systemid_len,
 			      odi->systemid, odi->systemid_len) &&
@@ -287,7 +280,6 @@ int _mach_odi(struct device *dev, void *find_data)
 			      odi->osdname, odi->osdname_len)) {
 		OSD_DEBUG("found device sysid_len=%d osdname=%d\n",
 			  odi->systemid_len, odi->osdname_len);
-		fot->oud = oud;
 		return 1;
 	} else {
 		return 0;
@@ -301,19 +293,19 @@ int _mach_odi(struct device *dev, void *find_data)
  */
 struct osd_dev *osduld_info_lookup(const struct osd_dev_info *odi)
 {
-	struct find_oud_t find = {.odi = odi};
-
-	find.dev = class_find_device(&osd_uld_class, NULL, &find, _mach_odi);
-	if (likely(find.dev)) {
+	struct device *dev = class_find_device(&osd_uld_class, NULL, odi, _match_odi);
+	if (likely(dev)) {
 		struct osd_dev_handle *odh = kzalloc(sizeof(*odh), GFP_KERNEL);
+		struct osd_uld_device *oud = container_of(dev,
+			struct osd_uld_device, class_dev);
 
 		if (unlikely(!odh)) {
-			put_device(find.dev);
+			put_device(dev);
 			return ERR_PTR(-ENOMEM);
 		}
 
-		odh->od = find.oud->od;
-		odh->oud = find.oud;
+		odh->od = oud->od;
+		odh->oud = oud;
 
 		return &odh->od;
 	}

drivers/scsi/scsi_transport_iscsi.c

@@ -183,10 +183,10 @@ static struct attribute_group iscsi_endpoint_group = {
 
 #define ISCSI_MAX_EPID -1
 
-static int iscsi_match_epid(struct device *dev, void *data)
+static int iscsi_match_epid(struct device *dev, const void *data)
 {
 	struct iscsi_endpoint *ep = iscsi_dev_to_endpoint(dev);
-	uint64_t *epid = (uint64_t *) data;
+	const uint64_t *epid = data;
 
 	return *epid == ep->id;
 }

drivers/spi/spi.c

@@ -1248,10 +1248,10 @@ int spi_master_resume(struct spi_master *master)
 }
 EXPORT_SYMBOL_GPL(spi_master_resume);
 
-static int __spi_master_match(struct device *dev, void *data)
+static int __spi_master_match(struct device *dev, const void *data)
 {
 	struct spi_master *m;
-	u16 *bus_num = data;
+	const u16 *bus_num = data;
 
 	m = container_of(dev, struct spi_master, dev);
 	return m->bus_num == *bus_num;

drivers/uwb/lc-rc.c

@@ -40,9 +40,9 @@
 
 #include "uwb-internal.h"
 
-static int uwb_rc_index_match(struct device *dev, void *data)
+static int uwb_rc_index_match(struct device *dev, const void *data)
 {
-	int *index = data;
+	const int *index = data;
 	struct uwb_rc *rc = dev_get_drvdata(dev);
 
 	if (rc->index == *index)
@@ -334,9 +334,9 @@ void uwb_rc_rm(struct uwb_rc *rc)
 }
 EXPORT_SYMBOL_GPL(uwb_rc_rm);
 
-static int find_rc_try_get(struct device *dev, void *data)
+static int find_rc_try_get(struct device *dev, const void *data)
 {
-	struct uwb_rc *target_rc = data;
+	const struct uwb_rc *target_rc = data;
 	struct uwb_rc *rc = dev_get_drvdata(dev);
 
 	if (rc == NULL) {
@@ -386,9 +386,9 @@ static inline struct uwb_rc *uwb_rc_get(struct uwb_rc *rc)
 	return rc;
 }
 
-static int find_rc_grandpa(struct device *dev, void *data)
+static int find_rc_grandpa(struct device *dev, const void *data)
 {
-	struct device *grandpa_dev = data;
+	const struct device *grandpa_dev = data;
 	struct uwb_rc *rc = dev_get_drvdata(dev);
 
 	if (rc->uwb_dev.dev.parent->parent == grandpa_dev) {
@@ -419,7 +419,7 @@ struct uwb_rc *uwb_rc_get_by_grandpa(const struct device *grandpa_dev)
 	struct device *dev;
 	struct uwb_rc *rc = NULL;
 
-	dev = class_find_device(&uwb_rc_class, NULL, (void *)grandpa_dev,
+	dev = class_find_device(&uwb_rc_class, NULL, grandpa_dev,
 				find_rc_grandpa);
 	if (dev)
 		rc = dev_get_drvdata(dev);
@@ -432,9 +432,9 @@ EXPORT_SYMBOL_GPL(uwb_rc_get_by_grandpa);
  *
  * @returns the pointer to the radio controller, properly referenced
  */
-static int find_rc_dev(struct device *dev, void *data)
+static int find_rc_dev(struct device *dev, const void *data)
 {
-	struct uwb_dev_addr *addr = data;
+	const struct uwb_dev_addr *addr = data;
 	struct uwb_rc *rc = dev_get_drvdata(dev);
 
 	if (rc == NULL) {
@@ -453,8 +453,7 @@ struct uwb_rc *uwb_rc_get_by_dev(const struct uwb_dev_addr *addr)
 	struct device *dev;
 	struct uwb_rc *rc = NULL;
 
-	dev = class_find_device(&uwb_rc_class, NULL, (void *)addr,
-				find_rc_dev);
+	dev = class_find_device(&uwb_rc_class, NULL, addr, find_rc_dev);
 	if (dev)
 		rc = dev_get_drvdata(dev);
 

include/linux/device.h

@@ -395,8 +395,8 @@ extern int class_for_each_device(struct class *class, struct device *start,
 				 void *data,
 				 int (*fn)(struct device *dev, void *data));
 extern struct device *class_find_device(struct class *class,
-					struct device *start, void *data,
-					int (*match)(struct device *, void *));
+					struct device *start, const void *data,
+					int (*match)(struct device *, const void *));
 
 struct class_attribute {
 	struct attribute attr;

include/linux/power_supply.h

@@ -224,7 +224,7 @@ struct power_supply_info {
 	int use_for_apm;
 };
 
-extern struct power_supply *power_supply_get_by_name(char *name);
+extern struct power_supply *power_supply_get_by_name(const char *name);
 extern void power_supply_changed(struct power_supply *psy);
 extern int power_supply_am_i_supplied(struct power_supply *psy);
 extern int power_supply_set_battery_charged(struct power_supply *psy);

include/linux/rtc.h

@@ -148,7 +148,7 @@ extern int rtc_initialize_alarm(struct rtc_device *rtc,
 extern void rtc_update_irq(struct rtc_device *rtc,
 			unsigned long num, unsigned long events);
 
-extern struct rtc_device *rtc_class_open(char *name);
+extern struct rtc_device *rtc_class_open(const char *name);
 extern void rtc_class_close(struct rtc_device *rtc);
 
 extern int rtc_irq_register(struct rtc_device *rtc,

init/do_mounts.c

@@ -81,9 +81,9 @@ struct uuidcmp {
  *
  * Returns 1 if the device matches, and 0 otherwise.
  */
-static int match_dev_by_uuid(struct device *dev, void *data)
+static int match_dev_by_uuid(struct device *dev, const void *data)
 {
-	struct uuidcmp *cmp = data;
+	const struct uuidcmp *cmp = data;
 	struct hd_struct *part = dev_to_part(dev);
 
 	if (!part->info)

kernel/power/suspend_test.c

@@ -112,7 +112,7 @@ static void __init test_wakealarm(struct rtc_device *rtc, suspend_state_t state)
 	rtc_set_alarm(rtc, &alm);
 }
 
-static int __init has_wakealarm(struct device *dev, void *name_ptr)
+static int __init has_wakealarm(struct device *dev, const void *data)
 {
 	struct rtc_device *candidate = to_rtc_device(dev);
 
@@ -121,7 +121,6 @@ static int __init has_wakealarm(struct device *dev, void *name_ptr)
 	if (!device_may_wakeup(candidate->dev.parent))
 		return 0;
 
-	*(const char **)name_ptr = dev_name(dev);
 	return 1;
 }
 
@@ -159,8 +158,8 @@ static int __init test_suspend(void)
 	static char		warn_no_rtc[] __initdata =
 		KERN_WARNING "PM: no wakealarm-capable RTC driver is ready\n";
 
-	char			*pony = NULL;
 	struct rtc_device	*rtc = NULL;
+	struct device		*dev;
 
 	/* PM is initialized by now; is that state testable? */
 	if (test_state == PM_SUSPEND_ON)
@@ -171,9 +170,9 @@ static int __init test_suspend(void)
 	}
 
 	/* RTCs have initialized by now too ... can we use one? */
-	class_find_device(rtc_class, NULL, &pony, has_wakealarm);
-	if (pony)
-		rtc = rtc_class_open(pony);
+	dev = class_find_device(rtc_class, NULL, NULL, has_wakealarm);
+	if (dev)
+		rtc = rtc_class_open(dev_name(dev));
 	if (!rtc) {
 		printk(warn_no_rtc);
 		goto done;

net/ieee802154/wpan-class.c

@@ -91,7 +91,7 @@ static struct class wpan_phy_class = {
 static DEFINE_MUTEX(wpan_phy_mutex);
 static int wpan_phy_idx;
 
-static int wpan_phy_match(struct device *dev, void *data)
+static int wpan_phy_match(struct device *dev, const void *data)
 {
 	return !strcmp(dev_name(dev), (const char *)data);
 }
@@ -103,8 +103,7 @@ struct wpan_phy *wpan_phy_find(const char *str)
 	if (WARN_ON(!str))
 		return NULL;
 
-	dev = class_find_device(&wpan_phy_class, NULL,
-			(void *)str, wpan_phy_match);
+	dev = class_find_device(&wpan_phy_class, NULL, str, wpan_phy_match);
 	if (!dev)
 		return NULL;
 

net/nfc/core.c

@@ -734,10 +734,10 @@ struct class nfc_class = {
 };
 EXPORT_SYMBOL(nfc_class);
 
-static int match_idx(struct device *d, void *data)
+static int match_idx(struct device *d, const void *data)
 {
 	struct nfc_dev *dev = to_nfc_dev(d);
-	unsigned int *idx = data;
+	const unsigned int *idx = data;
 
 	return dev->idx == *idx;
 }