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firmware: raspberrypi: Keep count of all consumers

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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>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
This commit is contained in:
Nicolas Saenz Julienne 2021-01-18 13:32:34 +01:00
parent a38fd87484
commit 1e7c57355a
2 changed files with 39 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
drivers/firmware/raspberrypi.c
View File

@ -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);

2
include/soc/bcm2835/raspberrypi-firmware.h
View File

@ -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;