From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: u.kleine-koenig@pengutronix.de, linux-kernel@vger.kernel.org,
Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
Florian Fainelli <f.fainelli@gmail.com>,
Ray Jui <rjui@broadcom.com>,
Scott Branden <sbranden@broadcom.com>,
bcm-kernel-feedback-list@broadcom.com
Cc: linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
devicetree@vger.kernel.org, wahrenst@gmx.net,
linux-input@vger.kernel.org, dmitry.torokhov@gmail.com,
gregkh@linuxfoundation.org, devel@driverdev.osuosl.org,
p.zabel@pengutronix.de, linux-gpio@vger.kernel.org,
linus.walleij@linaro.org, linux-clk@vger.kernel.org,
sboyd@kernel.org, linux-rpi-kernel@lists.infradead.org,
bgolaszewski@baylibre.com, andy.shevchenko@gmail.com
Subject: [PATCH v6 01/11] firmware: raspberrypi: Keep count of all consumers
Date: Fri, 11 Dec 2020 17:47:50 +0100 [thread overview]
Message-ID: <20201211164801.7838-2-nsaenzjulienne@suse.de> (raw)
In-Reply-To: <20201211164801.7838-1-nsaenzjulienne@suse.de>
When unbinding the firmware device we need to make sure it has no
consumers left. Otherwise we'd leave them with a firmware handle
pointing at freed memory.
Keep a reference count of all consumers and introduce rpi_firmware_put()
which will permit automatically decrease the reference count upon
unbinding consumer drivers.
Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
---
Changes since v5:
- Add comment to avoid people blindly switching the memory allocation
to the devm variant.
- Fix function documentation as per Florian's comment.
Changes since v3:
- Use kref instead of waiting on refcount
drivers/firmware/raspberrypi.c | 40 ++++++++++++++++++++--
include/soc/bcm2835/raspberrypi-firmware.h | 2 ++
2 files changed, 39 insertions(+), 3 deletions(-)
diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 30259dc9b805..b65e4c495772 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -7,6 +7,7 @@
*/
#include <linux/dma-mapping.h>
+#include <linux/kref.h>
#include <linux/mailbox_client.h>
#include <linux/module.h>
#include <linux/of_platform.h>
@@ -27,6 +28,8 @@ struct rpi_firmware {
struct mbox_chan *chan; /* The property channel. */
struct completion c;
u32 enabled;
+
+ struct kref consumers;
};
static DEFINE_MUTEX(transaction_lock);
@@ -225,12 +228,31 @@ static void rpi_register_clk_driver(struct device *dev)
-1, NULL, 0);
}
+static void rpi_firmware_delete(struct kref *kref)
+{
+ struct rpi_firmware *fw = container_of(kref, struct rpi_firmware,
+ consumers);
+
+ mbox_free_channel(fw->chan);
+ kfree(fw);
+}
+
+void rpi_firmware_put(struct rpi_firmware *fw)
+{
+ kref_put(&fw->consumers, rpi_firmware_delete);
+}
+EXPORT_SYMBOL_GPL(rpi_firmware_put);
+
static int rpi_firmware_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct rpi_firmware *fw;
- fw = devm_kzalloc(dev, sizeof(*fw), GFP_KERNEL);
+ /*
+ * Memory will be freed by rpi_firmware_delete() once all users have
+ * released their firmware handles. Don't use devm_kzalloc() here.
+ */
+ fw = kzalloc(sizeof(*fw), GFP_KERNEL);
if (!fw)
return -ENOMEM;
@@ -247,6 +269,7 @@ static int rpi_firmware_probe(struct platform_device *pdev)
}
init_completion(&fw->c);
+ kref_init(&fw->consumers);
platform_set_drvdata(pdev, fw);
@@ -275,7 +298,8 @@ static int rpi_firmware_remove(struct platform_device *pdev)
rpi_hwmon = NULL;
platform_device_unregister(rpi_clk);
rpi_clk = NULL;
- mbox_free_channel(fw->chan);
+
+ rpi_firmware_put(fw);
return 0;
}
@@ -284,16 +308,26 @@ static int rpi_firmware_remove(struct platform_device *pdev)
* rpi_firmware_get - Get pointer to rpi_firmware structure.
* @firmware_node: Pointer to the firmware Device Tree node.
*
+ * The reference to rpi_firmware has to be released with rpi_firmware_put().
+ *
* Returns NULL is the firmware device is not ready.
*/
struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node)
{
struct platform_device *pdev = of_find_device_by_node(firmware_node);
+ struct rpi_firmware *fw;
if (!pdev)
return NULL;
- return platform_get_drvdata(pdev);
+ fw = platform_get_drvdata(pdev);
+ if (!fw)
+ return NULL;
+
+ if (!kref_get_unless_zero(&fw->consumers))
+ return NULL;
+
+ return fw;
}
EXPORT_SYMBOL_GPL(rpi_firmware_get);
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index cc9cdbc66403..fdfef7fe40df 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -140,6 +140,7 @@ int rpi_firmware_property(struct rpi_firmware *fw,
u32 tag, void *data, size_t len);
int rpi_firmware_property_list(struct rpi_firmware *fw,
void *data, size_t tag_size);
+void rpi_firmware_put(struct rpi_firmware *fw);
struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node);
#else
static inline int rpi_firmware_property(struct rpi_firmware *fw, u32 tag,
@@ -154,6 +155,7 @@ static inline int rpi_firmware_property_list(struct rpi_firmware *fw,
return -ENOSYS;
}
+static inline void rpi_firmware_put(struct rpi_firmware *fw) { }
static inline struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node)
{
return NULL;
--
2.29.2
next prev parent reply other threads:[~2020-12-11 17:56 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-11 16:47 [PATCH v6 00/11] Raspberry Pi PoE HAT fan support Nicolas Saenz Julienne
2020-12-11 16:47 ` Nicolas Saenz Julienne [this message]
2020-12-13 5:14 ` [PATCH v6 01/11] firmware: raspberrypi: Keep count of all consumers Stephen Boyd
2020-12-16 10:37 ` Bartosz Golaszewski
2020-12-11 16:47 ` [PATCH v6 02/11] firmware: raspberrypi: Introduce devm_rpi_firmware_get() Nicolas Saenz Julienne
2020-12-16 10:35 ` Bartosz Golaszewski
2020-12-16 10:37 ` Nicolas Saenz Julienne
2020-12-11 16:47 ` [PATCH v6 03/11] clk: bcm: rpi: Release firmware handle on unbind Nicolas Saenz Julienne
2020-12-13 5:12 ` Stephen Boyd
2020-12-11 16:47 ` [PATCH v6 04/11] gpio: raspberrypi-exp: " Nicolas Saenz Julienne
2020-12-11 16:47 ` [PATCH v6 05/11] reset: raspberrypi: " Nicolas Saenz Julienne
2020-12-11 16:47 ` [PATCH v6 06/11] soc: bcm: raspberrypi-power: " Nicolas Saenz Julienne
2020-12-11 16:47 ` [PATCH v6 07/11] staging: vchiq: " Nicolas Saenz Julienne
2020-12-11 16:47 ` [PATCH v6 08/11] input: raspberrypi-ts: Release firmware handle when not needed Nicolas Saenz Julienne
2020-12-11 18:17 ` Florian Fainelli
2020-12-11 16:47 ` [PATCH v6 09/11] dt-bindings: pwm: Add binding for RPi firmware PWM bus Nicolas Saenz Julienne
2020-12-11 16:47 ` [PATCH v6 10/11] DO NOT MERGE: ARM: dts: Add RPi's official PoE hat support Nicolas Saenz Julienne
2020-12-11 16:48 ` [PATCH v6 11/11] pwm: Add Raspberry Pi Firmware based PWM bus Nicolas Saenz Julienne
2021-01-12 9:18 ` Uwe Kleine-König
2021-01-14 18:44 ` Nicolas Saenz Julienne
2021-01-11 21:02 ` [PATCH v6 00/11] Raspberry Pi PoE HAT fan support Nicolas Saenz Julienne
2021-01-12 8:52 ` Linus Walleij
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