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@linaro.org --- 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 f97d95b50773..6d81f6268b99 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