Re: [PATCH] tee: optee: Fix missing devices unregister during optee_remove

Hi Sumit,

On Tue, Oct 12, 2021 at 9:31 AM Sumit Garg sumit.garg@linaro.org wrote:

When OP-TEE driver is built as a module, OP-TEE client devices registered on TEE bus during probe should be unregistered during optee_remove. So implement optee_unregister_devices() accordingly.

Fixes: c3fa24af9244 ("tee: optee: add TEE bus device enumeration support") Reported-by: Sudeep Holla sudeep.holla@arm.com Signed-off-by: Sumit Garg sumit.garg@linaro.org

---

drivers/tee/optee/core.c | 3 +++ drivers/tee/optee/device.c | 22 ++++++++++++++++++++++ drivers/tee/optee/optee_private.h | 1 + 3 files changed, 26 insertions(+)

diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c index ccad3c7c8f6d..3915dc574503 100644 --- a/drivers/tee/optee/core.c +++ b/drivers/tee/optee/core.c @@ -586,6 +586,9 @@ static int optee_remove(struct platform_device *pdev) { struct optee *optee = platform_get_drvdata(pdev);

•   /* Unregister OP-TEE specific client devices on TEE bus */
  

•   optee_unregister_devices();
  

•   /*
     * Ask OP-TEE to free all cached shared memory objects to decrease
     * reference counters and also avoid wild pointers in secure world
  

diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c index ec1d24693eba..128a2d2a50a1 100644 --- a/drivers/tee/optee/device.c +++ b/drivers/tee/optee/device.c @@ -53,6 +53,13 @@ static int get_devices(struct tee_context *ctx, u32 session, return 0; }

+static void optee_release_device(struct device *dev) +{

•   struct tee_client_device *optee_device = to_tee_client_device(dev);
  

•   kfree(optee_device);
  

+}

static int optee_register_device(const uuid_t *device_uuid) { struct tee_client_device *optee_device = NULL; @@ -63,6 +70,7 @@ static int optee_register_device(const uuid_t *device_uuid) return -ENOMEM;

    optee_device->dev.bus = &tee_bus_type;

•   optee_device->dev.release = optee_release_device;
    if (dev_set_name(&optee_device->dev, "optee-ta-%pUb", device_uuid)) {
            kfree(optee_device);
            return -ENOMEM;
  

@@ -154,3 +162,17 @@ int optee_enumerate_devices(u32 func) { return __optee_enumerate_devices(func); }

+static int __optee_unregister_device(struct device *dev, void *data) +{

•   if (!strncmp(dev_name(dev), "optee-ta", strlen("optee-ta")))
  

•           device_unregister(dev);
  

•   return 0;
  

+}

+void optee_unregister_devices(void) +{

•   bus_for_each_dev(&tee_bus_type, NULL, NULL,
  

•                    __optee_unregister_device);
  

I had something like this in mind too, but there's one potential problem with this approach. What if there's more than one OP-TEE driver with TAs here? It seems that we'll remove TAs from other drivers too then.

This is not likely to be a problem at upstream for the moment so I might be enough just to keep this in mind if/when the OP-TEE driver is extended in a way that there can be multiple OP-TEEs handled.

Cheers, Jens