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authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2021-12-30 18:02:50 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-12-30 19:44:06 +0300
commitc18e2760308e30f007fa24b558b87c39d7e86ff1 (patch)
treeae57aa609914f9df5aebc50dd3a1a11238a6ac47 /include/linux/counter.h
parente152833b2c97b043bdc5f650eda2f432cf1a21a3 (diff)
downloadlinux-c18e2760308e30f007fa24b558b87c39d7e86ff1.tar.xz
counter: Provide alternative counter registration functions
The current implementation gets device lifetime tracking wrong. The problem is that allocation of struct counter_device is controlled by the individual drivers but this structure contains a struct device that might have to live longer than a driver is bound. As a result a command sequence like: { sleep 5; echo bang; } > /dev/counter0 & sleep 1; echo 40000000.timer:counter > /sys/bus/platform/drivers/stm32-timer-counter/unbind can keep a reference to the struct device and unbinding results in freeing the memory occupied by this device resulting in an oops. This commit provides two new functions (plus some helpers): - counter_alloc() to allocate a struct counter_device that is automatically freed once the embedded struct device is released - counter_add() to register such a device. Note that this commit doesn't fix any issues, all drivers have to be converted to these new functions to correct the lifetime problems. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20211230150300.72196-14-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/counter.h')
-rw-r--r--include/linux/counter.h15
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/counter.h b/include/linux/counter.h
index 627f1757f6bb..ed8d5820f0d1 100644
--- a/include/linux/counter.h
+++ b/include/linux/counter.h
@@ -327,14 +327,29 @@ struct counter_device {
spinlock_t events_in_lock;
struct mutex events_out_lock;
struct mutex ops_exist_lock;
+
+ /*
+ * This can go away once all drivers are converted to
+ * counter_alloc()/counter_add().
+ */
+ bool legacy_device;
};
void *counter_priv(const struct counter_device *const counter);
int counter_register(struct counter_device *const counter);
+
+struct counter_device *counter_alloc(size_t sizeof_priv);
+void counter_put(struct counter_device *const counter);
+int counter_add(struct counter_device *const counter);
+
void counter_unregister(struct counter_device *const counter);
int devm_counter_register(struct device *dev,
struct counter_device *const counter);
+struct counter_device *devm_counter_alloc(struct device *dev,
+ size_t sizeof_priv);
+int devm_counter_add(struct device *dev,
+ struct counter_device *const counter);
void counter_push_event(struct counter_device *const counter, const u8 event,
const u8 channel);