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 make sure they all finished
unbinding before we do.
Suggested-by: Uwe Kleine-König <u.kleine-koe...@pengutronix.de>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulie...@suse.de>
---
@Uwe: I didn't found it necessary to call 'try_module_get()' as the rest
of modules depend on the 'rpi_firmware_get/put()' symbols which already
block users from unloading the module prematurely.
drivers/firmware/raspberrypi.c | 30 +++++++++++++++++++++-
include/soc/bcm2835/raspberrypi-firmware.h | 3 +++
2 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 2371d08bdd17..e5ba609e3985 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -11,7 +11,9 @@
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
+#include <linux/refcount.h>
#include <linux/slab.h>
+#include <linux/wait.h>
#include <soc/bcm2835/raspberrypi-firmware.h>
#define MBOX_MSG(chan, data28) (((data28) & ~0xf) | ((chan) & 0xf))
@@ -27,6 +29,9 @@ struct rpi_firmware {
struct mbox_chan *chan; /* The property channel. */
struct completion c;
u32 enabled;
+
+ refcount_t consumers;
+ wait_queue_head_t wait;
};
static DEFINE_MUTEX(transaction_lock);
@@ -247,6 +252,8 @@ static int rpi_firmware_probe(struct platform_device *pdev)
}
init_completion(&fw->c);
+ refcount_set(&fw->consumers, 1);
+ init_waitqueue_head(&fw->wait);
platform_set_drvdata(pdev, fw);
@@ -275,6 +282,8 @@ static int rpi_firmware_remove(struct platform_device *pdev)
rpi_hwmon = NULL;
platform_device_unregister(rpi_clk);
rpi_clk = NULL;
+
+ wait_event(fw->wait, refcount_dec_if_one(&fw->consumers));
mbox_free_channel(fw->chan);
return 0;
@@ -289,14 +298,33 @@ static int rpi_firmware_remove(struct platform_device
*pdev)
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 (!refcount_inc_not_zero(&fw->consumers))
+ return NULL;
+
+ return fw;
}
EXPORT_SYMBOL_GPL(rpi_firmware_get);
+/**
+ * rpi_firmware_put - Put pointer to rpi_firmware structure.
+ * @rpi_firmware: Pointer to struct rpi_firmware
+ */
+void rpi_firmware_put(struct rpi_firmware *fw)
+{
+ refcount_dec(&fw->consumers);
+ wake_up(&fw->wait);
+}
+EXPORT_SYMBOL_GPL(rpi_firmware_put);
+
static const struct of_device_id rpi_firmware_of_match[] = {
{ .compatible = "raspberrypi,bcm2835-firmware", },
{},
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h
b/include/soc/bcm2835/raspberrypi-firmware.h
index cc9cdbc66403..7836ea51fbdf 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -141,6 +141,7 @@ int rpi_firmware_property(struct rpi_firmware *fw,
int rpi_firmware_property_list(struct rpi_firmware *fw,
void *data, size_t tag_size);
struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node);
+void rpi_firmware_put(struct rpi_firmware *fw);
#else
static inline int rpi_firmware_property(struct rpi_firmware *fw, u32 tag,
void *data, size_t len)
@@ -158,6 +159,8 @@ static inline struct rpi_firmware *rpi_firmware_get(struct
device_node *firmware
{
return NULL;
}
+
+void rpi_firmware_put(struct rpi_firmware *fw) { }
#endif
#endif /* __SOC_RASPBERRY_FIRMWARE_H__ */
--
2.28.0
_______________________________________________
devel mailing list
de...@linuxdriverproject.org
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
