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Subject[PATCH v3 1/3] leds: triggers: provide led_trigger_register_format()
Date
This allows one to simplify drivers that provide a trigger with a
non-constant name (e.g. one trigger per device with the trigger name
depending on the device's name).

Internally the memory the name member of struct led_trigger points to
now always allocated dynamically instead of just taken from the caller.

The function led_trigger_rename_static() must be changed accordingly and
was renamed to led_trigger_rename() for consistency, with the only user
adapted.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
drivers/leds/led-triggers.c | 84 +++++++++++++++++++++++++++----------
drivers/net/can/led.c | 6 +--
include/linux/leds.h | 30 +++++++------
3 files changed, 81 insertions(+), 39 deletions(-)

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 431123b048a2..5d8bb504b07b 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -175,18 +175,34 @@ void led_trigger_set_default(struct led_classdev *led_cdev)
}
EXPORT_SYMBOL_GPL(led_trigger_set_default);

-void led_trigger_rename_static(const char *name, struct led_trigger *trig)
+int led_trigger_rename(struct led_trigger *trig, const char *fmt, ...)
{
- /* new name must be on a temporary string to prevent races */
- BUG_ON(name == trig->name);
+ const char *prevname;
+ const char *newname;
+ va_list args;
+
+ if (!trig)
+ return 0;
+
+ va_start(args, fmt);
+ newname = kvasprintf_const(GFP_KERNEL, fmt, args);
+ va_end(args);
+
+ if (!newname) {
+ pr_err("Failed to allocate new name for trigger %s\n", trig->name);
+ return -ENOMEM;
+ }

down_write(&triggers_list_lock);
- /* this assumes that trig->name was originaly allocated to
- * non constant storage */
- strcpy((char *)trig->name, name);
+ prevname = trig->name;
+ trig->name = newname;
up_write(&triggers_list_lock);
+
+ kfree_const(prevname);
+
+ return 0;
}
-EXPORT_SYMBOL_GPL(led_trigger_rename_static);
+EXPORT_SYMBOL_GPL(led_trigger_rename);

/* LED Trigger Interface */

@@ -333,34 +349,56 @@ void led_trigger_blink_oneshot(struct led_trigger *trig,
}
EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);

-void led_trigger_register_simple(const char *name, struct led_trigger **tp)
+int led_trigger_register_format(struct led_trigger **tp, const char *fmt, ...)
{
+ va_list args;
struct led_trigger *trig;
- int err;
+ int err = -ENOMEM;
+ const char *name;
+
+ va_start(args, fmt);
+ name = kvasprintf_const(GFP_KERNEL, fmt, args);
+ va_end(args);

trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);

- if (trig) {
- trig->name = name;
- err = led_trigger_register(trig);
- if (err < 0) {
- kfree(trig);
- trig = NULL;
- pr_warn("LED trigger %s failed to register (%d)\n",
- name, err);
- }
- } else {
- pr_warn("LED trigger %s failed to register (no memory)\n",
- name);
- }
+ if (!name || !trig)
+ goto err;
+
+ trig->name = name;
+
+ err = led_trigger_register(trig);
+ if (err < 0)
+ goto err;
+
*tp = trig;
+
+ return 0;
+
+err:
+ kfree(trig);
+ kfree_const(name);
+
+ *tp = NULL;
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(led_trigger_register_format);
+
+void led_trigger_register_simple(const char *name, struct led_trigger **tp)
+{
+ int ret = led_trigger_register_format(tp, "%s", name);
+ if (ret < 0)
+ pr_warn("LED trigger %s failed to register (%d)\n", name, ret);
}
EXPORT_SYMBOL_GPL(led_trigger_register_simple);

void led_trigger_unregister_simple(struct led_trigger *trig)
{
- if (trig)
+ if (trig) {
led_trigger_unregister(trig);
+ kfree_const(trig->name);
+ }
kfree(trig);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
diff --git a/drivers/net/can/led.c b/drivers/net/can/led.c
index c1b667675fa1..2d7d1b0d20f9 100644
--- a/drivers/net/can/led.c
+++ b/drivers/net/can/led.c
@@ -115,13 +115,13 @@ static int can_led_notifier(struct notifier_block *nb, unsigned long msg,

if (msg == NETDEV_CHANGENAME) {
snprintf(name, sizeof(name), "%s-tx", netdev->name);
- led_trigger_rename_static(name, priv->tx_led_trig);
+ led_trigger_rename(priv->tx_led_trig, name);

snprintf(name, sizeof(name), "%s-rx", netdev->name);
- led_trigger_rename_static(name, priv->rx_led_trig);
+ led_trigger_rename(priv->rx_led_trig, name);

snprintf(name, sizeof(name), "%s-rxtx", netdev->name);
- led_trigger_rename_static(name, priv->rxtx_led_trig);
+ led_trigger_rename(priv->rxtx_led_trig, name);
}

return NOTIFY_DONE;
diff --git a/include/linux/leds.h b/include/linux/leds.h
index b7e82550e655..e706c28bb35b 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -275,6 +275,8 @@ extern void led_trigger_unregister(struct led_trigger *trigger);
extern int devm_led_trigger_register(struct device *dev,
struct led_trigger *trigger);

+extern int led_trigger_register_format(struct led_trigger **trigger,
+ const char *fmt, ...);
extern void led_trigger_register_simple(const char *name,
struct led_trigger **trigger);
extern void led_trigger_unregister_simple(struct led_trigger *trigger);
@@ -298,28 +300,25 @@ static inline void *led_get_trigger_data(struct led_classdev *led_cdev)
}

/**
- * led_trigger_rename_static - rename a trigger
- * @name: the new trigger name
+ * led_trigger_rename - rename a trigger
* @trig: the LED trigger to rename
+ * @fmt: format string for new name
*
- * Change a LED trigger name by copying the string passed in
- * name into current trigger name, which MUST be large
- * enough for the new string.
- *
- * Note that name must NOT point to the same string used
- * during LED registration, as that could lead to races.
- *
- * This is meant to be used on triggers with statically
- * allocated name.
+ * rebaptize the given trigger.
*/
-extern void led_trigger_rename_static(const char *name,
- struct led_trigger *trig);
+extern int led_trigger_rename(struct led_trigger *trig, const char *fmt, ...);

#else

/* Trigger has no members */
struct led_trigger {};

+static inline int led_trigger_register_format(struct led_trigger **trigger,
+ const char *fmt, ...)
+{
+ return 0;
+}
+
/* Trigger inline empty functions */
static inline void led_trigger_register_simple(const char *name,
struct led_trigger **trigger) {}
@@ -342,6 +341,11 @@ static inline void *led_get_trigger_data(struct led_classdev *led_cdev)
return NULL;
}

+static inline int led_trigger_rename(struct led_trigger *trig, const char *fmt, ...)
+{
+ return 0;
+}
+
#endif /* CONFIG_LEDS_TRIGGERS */

/* Trigger specific functions */
--
2.17.0
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