5.4-stable review patch. If anyone has any objections, please let me know.
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From: Sumit Garg sumit.garg@linaro.org
commit 70b0d6b0a199c5a3ee6c72f5e61681ed6f759612 upstream.
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 Reviewed-by: Arnd Bergmann arnd@arndb.de Reviewed-by: Jens Wiklander jens.wiklander@linaro.org Signed-off-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tee/optee/supp.c | 35 ++++++++--------------------------- 1 file changed, 8 insertions(+), 27 deletions(-)
--- a/drivers/tee/optee/supp.c +++ b/drivers/tee/optee/supp.c @@ -80,7 +80,6 @@ u32 optee_supp_thrd_req(struct tee_conte 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_conte /* * 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;