From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Date: Fri, 2 Dec 2022 18:35:10 +0000 (+0100)
Subject: pwm: Reduce time the pwm_lock mutex is held in pwmchip_add()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c8135b5174145a65c72c4303f2752cc8cecf8d08;p=linux.git

pwm: Reduce time the pwm_lock mutex is held in pwmchip_add()

This simplifies error handling as the need for goto error handling goes
away and at the end of the function the code can be simplified as this
code isn't used in the error case any more.

Now memory allocation and the call to of_pwmchip_add() are done without
holding the lock. Both don't access the data structures protected by
&pwm_lock.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221117211143.3817381-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index ebe06efe9de52..2338119a09d89 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -272,20 +272,21 @@ int pwmchip_add(struct pwm_chip *chip)
 	if (!pwm_ops_check(chip))
 		return -EINVAL;
 
+	chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL);
+	if (!chip->pwms)
+		return -ENOMEM;
+
 	mutex_lock(&pwm_lock);
 
 	ret = alloc_pwms(chip->npwm);
-	if (ret < 0)
-		goto out;
+	if (ret < 0) {
+		mutex_unlock(&pwm_lock);
+		kfree(chip->pwms);
+		return ret;
+	}
 
 	chip->base = ret;
 
-	chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL);
-	if (!chip->pwms) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
 	for (i = 0; i < chip->npwm; i++) {
 		pwm = &chip->pwms[i];
 
@@ -301,18 +302,14 @@ int pwmchip_add(struct pwm_chip *chip)
 	INIT_LIST_HEAD(&chip->list);
 	list_add(&chip->list, &pwm_chips);
 
-	ret = 0;
+	mutex_unlock(&pwm_lock);
 
 	if (IS_ENABLED(CONFIG_OF))
 		of_pwmchip_add(chip);
 
-out:
-	mutex_unlock(&pwm_lock);
-
-	if (!ret)
-		pwmchip_sysfs_export(chip);
+	pwmchip_sysfs_export(chip);
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(pwmchip_add);