[PATCH v2] tee: optee: Fix supplicant based device enumeration

[Sumit Garg <sumit.garg@linaro.org>]

Currently supplicant dependent optee device enumeration only registers
devices whenever tee-supplicant is invoked for the first time. But it
forgets to remove devices when tee-supplicant daemon stops running and
closes its context gracefully. This leads to following error for fTPM
driver during reboot/shutdown:

[   73.466791] tpm tpm0: ftpm_tee_tpm_op_send: SUBMIT_COMMAND invoke error: 0xffff3024

Fix this by separating supplicant dependent devices so that the
user-space service can detach supplicant devices before closing the
supplicant. While at it use the global system workqueue for OP-TEE bus
scanning work rather than our own custom one.

Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Link: https://github.com/OP-TEE/optee_os/issues/6094
Fixes: 5f178bb71e3a ("optee: enable support for multi-stage bus enumeration")
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---

Changes in v2:

Apologies for taking it too long push this v2. Actually I did brainstorm
how to best fix this tee-supplicant dependent device probing. Its hard
to predict the lifetime of user-space daemon from kernel space. So
following is the least intrusive approach:

- Use device names to seperate out tee-supplicant dependent devices via
  this patch.
- Since user-space service is aware about tee-supplicant lifespan, so
  allow the user-space service to unbind tee-supplicant dependent
  devices before killing the supplicant. Following command has to be
  added to the tee-supplicant service file.

  $ for dev in /sys/bus/tee/devices/*; do if [[ "$dev" == *"optee-ta-supp-"* ]]; \
        then echo $(basename "$dev") > $dev/driver/unbind; fi done

 drivers/tee/optee/core.c          | 13 ++-----------
 drivers/tee/optee/device.c        | 13 ++++++++++---
 drivers/tee/optee/optee_private.h |  2 --
 3 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index d01ca47f7bde..8ee3c71bd989 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -15,7 +15,6 @@
 #include <linux/string.h>
 #include <linux/tee_drv.h>
 #include <linux/types.h>
-#include <linux/workqueue.h>
 #include "optee_private.h"
 
 int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
@@ -110,12 +109,7 @@ int optee_open(struct tee_context *ctx, bool cap_memref_null)
 
 		if (!optee->scan_bus_done) {
 			INIT_WORK(&optee->scan_bus_work, optee_bus_scan);
-			optee->scan_bus_wq = create_workqueue("optee_bus_scan");
-			if (!optee->scan_bus_wq) {
-				kfree(ctxdata);
-				return -ECHILD;
-			}
-			queue_work(optee->scan_bus_wq, &optee->scan_bus_work);
+			schedule_work(&optee->scan_bus_work);
 			optee->scan_bus_done = true;
 		}
 	}
@@ -159,10 +153,7 @@ void optee_release_supp(struct tee_context *ctx)
 	struct optee *optee = tee_get_drvdata(ctx->teedev);
 
 	optee_release_helper(ctx, optee_close_session_helper);
-	if (optee->scan_bus_wq) {
-		destroy_workqueue(optee->scan_bus_wq);
-		optee->scan_bus_wq = NULL;
-	}
+
 	optee_supp_release(&optee->supp);
 }
 
diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c
index 64f0e047c23d..78fc0a15c463 100644
--- a/drivers/tee/optee/device.c
+++ b/drivers/tee/optee/device.c
@@ -60,9 +60,10 @@ static void optee_release_device(struct device *dev)
 	kfree(optee_device);
 }
 
-static int optee_register_device(const uuid_t *device_uuid)
+static int optee_register_device(const uuid_t *device_uuid, u32 func)
 {
 	struct tee_client_device *optee_device = NULL;
+	const char *dev_name_fmt = NULL;
 	int rc;
 
 	optee_device = kzalloc(sizeof(*optee_device), GFP_KERNEL);
@@ -71,7 +72,13 @@ static int optee_register_device(const uuid_t *device_uuid)
 
 	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)) {
+
+	if (func == PTA_CMD_GET_DEVICES_SUPP)
+		dev_name_fmt = "optee-ta-supp-%pUb";
+	else
+		dev_name_fmt = "optee-ta-%pUb";
+
+	if (dev_set_name(&optee_device->dev, dev_name_fmt, device_uuid)) {
 		kfree(optee_device);
 		return -ENOMEM;
 	}
@@ -142,7 +149,7 @@ static int __optee_enumerate_devices(u32 func)
 	num_devices = shm_size / sizeof(uuid_t);
 
 	for (idx = 0; idx < num_devices; idx++) {
-		rc = optee_register_device(&device_uuid[idx]);
+		rc = optee_register_device(&device_uuid[idx], func);
 		if (rc)
 			goto out_shm;
 	}
diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
index 6dcecb83c893..af4aa266c3fb 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -193,7 +193,6 @@ struct optee_ops {
  * @pool:		shared memory pool
  * @rpc_param_count:	If > 0 number of RPC parameters to make room for
  * @scan_bus_done	flag if device registation was already done.
- * @scan_bus_wq		workqueue to scan optee bus and register optee drivers
  * @scan_bus_work	workq to scan optee bus and register optee drivers
  */
 struct optee {
@@ -212,7 +211,6 @@ struct optee {
 	struct tee_shm_pool *pool;
 	unsigned int rpc_param_count;
 	bool   scan_bus_done;
-	struct workqueue_struct *scan_bus_wq;
 	struct work_struct scan_bus_work;
 };
 
-- 
2.34.1