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Subject[PATCH v3 2/4] tee: add supp_nowait flag in tee_context struct
Date
This flag indicates that requests in this context should not wait for
tee-supplicant daemon to be started if not present and just return
with an error code. It is needed for requests which should be
non-blocking in nature like ones arising from TEE based kernel drivers
or any in kernel api that uses TEE internal client interface.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
drivers/tee/optee/supp.c | 10 +++++++++-
drivers/tee/tee_core.c | 13 +++++++++++++
include/linux/tee_drv.h | 6 ++++++
3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c
index 43626e1..92f56b8 100644
--- a/drivers/tee/optee/supp.c
+++ b/drivers/tee/optee/supp.c
@@ -88,10 +88,18 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params,
{
struct optee *optee = tee_get_drvdata(ctx->teedev);
struct optee_supp *supp = &optee->supp;
- struct optee_supp_req *req = kzalloc(sizeof(*req), GFP_KERNEL);
+ struct optee_supp_req *req;
bool interruptable;
u32 ret;

+ /*
+ * Return in case there is no supplicant available and
+ * non-blocking request.
+ */
+ if (!supp->ctx && ctx->supp_nowait)
+ return TEEC_ERROR_COMMUNICATION;
+
+ req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req)
return TEEC_ERROR_OUT_OF_MEMORY;

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index a685940..eed83bd 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -105,6 +105,11 @@ static int tee_open(struct inode *inode, struct file *filp)
if (IS_ERR(ctx))
return PTR_ERR(ctx);

+ /*
+ * Default user-space behaviour is to wait for tee-supplicant
+ * if not present for any requests in this context.
+ */
+ ctx->supp_nowait = false;
filp->private_data = ctx;
return 0;
}
@@ -981,6 +986,14 @@ tee_client_open_context(struct tee_context *start,
} while (IS_ERR(ctx) && PTR_ERR(ctx) != -ENOMEM);

put_device(put_dev);
+ /*
+ * Default behaviour for in kernel client is to not wait for
+ * tee-supplicant if not present for any requests in this context.
+ * Also this flag could be configured again before call to
+ * tee_client_open_session() if any in kernel client requires
+ * different behaviour.
+ */
+ ctx->supp_nowait = true;
return ctx;
}
EXPORT_SYMBOL_GPL(tee_client_open_context);
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index ed16bf1..fe1a920 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -49,6 +49,11 @@ struct tee_shm_pool;
* @releasing: flag that indicates if context is being released right now.
* It is needed to break circular dependency on context during
* shared memory release.
+ * @supp_nowait: flag that indicates that requests in this context should not
+ * wait for tee-supplicant daemon to be started if not present
+ * and just return with an error code. It is needed for requests
+ * that arises from TEE based kernel drivers that should be
+ * non-blocking in nature.
*/
struct tee_context {
struct tee_device *teedev;
@@ -56,6 +61,7 @@ struct tee_context {
void *data;
struct kref refcount;
bool releasing;
+ bool supp_nowait;
};

struct tee_param_memref {
--
2.7.4
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