linux-kernel - [PATCH v2 1/4] pwm: Document variables protected by pwm

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Message-Id: <20221117211143.3817381-2-u.kleine-koenig@pengutronix.de>
Date:   Thu, 17 Nov 2022 22:11:40 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     linux-pwm@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org, kernel@...gutronix.de
Subject: [PATCH v2 1/4] pwm: Document variables protected by pwm_lock

To simplify validation of the used locking, document for the global pwm
mutex what it actually protects against concurrent access. Also note for
two functions modifying these that pwm_lock is held by the caller.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
 drivers/pwm/core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index d333e7422f4a..ebe06efe9de5 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -27,7 +27,10 @@
 
 static DEFINE_MUTEX(pwm_lookup_lock);
 static LIST_HEAD(pwm_lookup_list);
+
+/* protects access to pwm_chips, allocated_pwms, and pwm_tree */
 static DEFINE_MUTEX(pwm_lock);
+
 static LIST_HEAD(pwm_chips);
 static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
 static RADIX_TREE(pwm_tree, GFP_KERNEL);
@@ -37,6 +40,7 @@ static struct pwm_device *pwm_to_device(unsigned int pwm)
 	return radix_tree_lookup(&pwm_tree, pwm);
 }
 
+/* Called with pwm_lock held */
 static int alloc_pwms(unsigned int count)
 {
 	unsigned int start;
@@ -50,6 +54,7 @@ static int alloc_pwms(unsigned int count)
 	return start;
 }
 
+/* Called with pwm_lock held */
 static void free_pwms(struct pwm_chip *chip)
 {
 	unsigned int i;
-- 
2.38.1