Adds tee_dev_open_helper() and tee_dev_ctx_put() to make it easier to
create a driver internal struct tee_context without the usual
tee_device_get() on the struct tee_device as that adds a circular
reference counter dependency and would prevent the struct tee_device
from ever being released again.
Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
---
drivers/tee/tee_core.c | 33 ++++++++++++++++++++++++---------
include/linux/tee_drv.h | 27 +++++++++++++++++++++++++++
2 files changed, 51 insertions(+), 9 deletions(-)
diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 85102d12d716..3beb682684a8 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -43,14 +43,11 @@ static DEFINE_SPINLOCK(driver_lock);
static struct class *tee_class;
static dev_t tee_devt;
-static struct tee_context *teedev_open(struct tee_device *teedev)
+struct tee_context *tee_dev_open_helper(struct tee_device *teedev)
{
int rc;
struct tee_context *ctx;
- if (!tee_device_get(teedev))
- return ERR_PTR(-EINVAL);
-
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx) {
rc = -ENOMEM;
@@ -66,10 +63,30 @@ static struct tee_context *teedev_open(struct tee_device *teedev)
return ctx;
err:
kfree(ctx);
- tee_device_put(teedev);
return ERR_PTR(rc);
}
+EXPORT_SYMBOL_GPL(tee_dev_open_helper);
+
+void tee_dev_ctx_put(struct tee_context *ctx)
+{
+ teedev_ctx_put(ctx);
+}
+EXPORT_SYMBOL_GPL(tee_dev_ctx_put);
+
+static struct tee_context *teedev_open(struct tee_device *teedev)
+{
+ struct tee_context *ctx;
+
+ if (!tee_device_get(teedev))
+ return ERR_PTR(-EINVAL);
+
+ ctx = tee_dev_open_helper(teedev);
+ if (IS_ERR(ctx))
+ tee_device_put(teedev);
+
+ return ctx;
+}
void teedev_ctx_get(struct tee_context *ctx)
{
@@ -90,10 +107,8 @@ static void teedev_ctx_release(struct kref *ref)
void teedev_ctx_put(struct tee_context *ctx)
{
- if (ctx->releasing)
- return;
-
- kref_put(&ctx->refcount, teedev_ctx_release);
+ if (ctx && !ctx->releasing)
+ kref_put(&ctx->refcount, teedev_ctx_release);
}
static void teedev_close_context(struct tee_context *ctx)
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index 54269e47ac9a..f592ba4e9561 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -456,6 +456,33 @@ static inline int tee_shm_get_id(struct tee_shm *shm)
*/
struct tee_shm *tee_shm_get_from_id(struct tee_context *ctx, int id);
+/**
+ * tee_dev_open_helper() - helper function to make a struct tee_context
+ * @teedev: Device to open
+ *
+ * Creates the struct tee_context without increasing the reference counter
+ * on @teedev. This is needed for instance when a driver need an internal
+ * struct tee_context to operate on. By skipping the reference counter
+ * the circular dependency is broken.
+ *
+ * Note that this struct tee_context need special care when freeing in
+ * order to avoid the normal put on the struct tee_device.
+ * tee_dev_ctx_put() is the best choice for this.
+ *
+ * @returns a pointer 'struct tee_context' on success or an ERR_PTR on failure
+ */
+struct tee_context *tee_dev_open_helper(struct tee_device *teedev);
+
+/**
+ * tee_dev_ctx_put() - helper function to release a struct tee_context
+ * @ctx: The struct tee_context to release
+ *
+ * Note that this function doesn't do a tee_device_put() on the internal
+ * struct tee_device so this function should normal only be used when
+ * releasing a struct tee_context obtained with tee_dev_open_helper().
+ */
+void tee_dev_ctx_put(struct tee_context *ctx);
+
/**
* tee_client_open_context() - Open a TEE context
* @start: if not NULL, continue search after this context
--
2.31.1
