linux-kernel - [PATCH] driver core: platform: document registration-failure requirement

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Message-Id: <20211222085229.11657-1-johan@kernel.org>
Date:   Wed, 22 Dec 2021 09:52:29 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Rafał Miłecki <zajec5@...il.com>,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>
Subject: [PATCH] driver core: platform: document registration-failure requirement

Add an explicit comment to document that the reference initialised by
platform_device_register() needs to be released by a call to
platform_device_put() also when registration fails (cf.
device_register()).

Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/base/platform.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 598acf93a360..38fdcbdba4a4 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -762,6 +762,10 @@ EXPORT_SYMBOL_GPL(platform_device_del);
 /**
  * platform_device_register - add a platform-level device
  * @pdev: platform device we're adding
+ *
+ * NOTE: _Never_ directly free @pdev after calling this function, even if it
+ * returned an error! Always use platform_put_device() to give up the
+ * reference initialised in this function instead.
  */
 int platform_device_register(struct platform_device *pdev)
 {
-- 
2.32.0