OP-TEE supplicant is a user-space daemon and it's possible for it be hung or crashed or killed in the middle of processing an OP-TEE RPC call. It becomes more complicated when there is incorrect shutdown ordering of the supplicant process vs the OP-TEE client application which can eventually lead to system hang-up waiting for the closure of the client application.
Allow the client process waiting in kernel for supplicant response to be killed rather than indefinitely waiting in an unkillable state. Also, a normal uninterruptible wait should not have resulted in the hung-task watchdog getting triggered, but the endless loop would.
This fixes issues observed during system reboot/shutdown when supplicant got hung for some reason or gets crashed/killed which lead to client getting hung in an unkillable state. It in turn lead to system being in hung up state requiring hard power off/on to recover.
Fixes: 4fb0a5eb364d ("tee: add OP-TEE driver") Suggested-by: Arnd Bergmann arnd@arndb.de Cc: stable@vger.kernel.org Signed-off-by: Sumit Garg sumit.garg@linaro.org ---
Changes in v3: - Use mutex_lock() instead of mutex_lock_killable(). - Update commit message to incorporate Arnd's feedback.
Changes in v2: - Switch to killable wait instead as suggested by Arnd instead of supplicant timeout. It atleast allow the client to wait for supplicant in killable state which in turn allows system to reboot or shutdown gracefully.
drivers/tee/optee/supp.c | 35 ++++++++--------------------------- 1 file changed, 8 insertions(+), 27 deletions(-)
diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c index 322a543b8c27..d0f397c90242 100644 --- a/drivers/tee/optee/supp.c +++ b/drivers/tee/optee/supp.c @@ -80,7 +80,6 @@ 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; - bool interruptable; u32 ret;
/* @@ -111,36 +110,18 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params, /* * Wait for supplicant to process and return result, once we've * returned from wait_for_completion(&req->c) successfully we have - * exclusive access again. + * exclusive access again. Allow the wait to be killable such that + * the wait doesn't turn into an indefinite state if the supplicant + * gets hung for some reason. */ - while (wait_for_completion_interruptible(&req->c)) { + if (wait_for_completion_killable(&req->c)) { mutex_lock(&supp->mutex); - interruptable = !supp->ctx; - if (interruptable) { - /* - * There's no supplicant available and since the - * supp->mutex currently is held none can - * become available until the mutex released - * again. - * - * Interrupting an RPC to supplicant is only - * allowed as a way of slightly improving the user - * experience in case the supplicant hasn't been - * started yet. During normal operation the supplicant - * will serve all requests in a timely manner and - * interrupting then wouldn't make sense. - */ - if (req->in_queue) { - list_del(&req->link); - req->in_queue = false; - } + if (req->in_queue) { + list_del(&req->link); + req->in_queue = false; } mutex_unlock(&supp->mutex); - - if (interruptable) { - req->ret = TEEC_ERROR_COMMUNICATION; - break; - } + req->ret = TEEC_ERROR_COMMUNICATION; }
ret = req->ret;