Hi Rouven,

On Wed, Jul 3, 2019 at 12:04 PM Rouven Czerwinski r.czerwinski@pengutronix.de wrote:

If the kernel is compiled with CONFIG_PREEMPT_VOLUNTARY and OP-TEE is executing a long running workload, the following errors are raised:

[ 1705.971228] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [ 1705.977195] rcu: (detected by 0, t=2102 jiffies, g=51977, q=3) [ 1705.983152] rcu: All QSes seen, last rcu_sched kthread activity 2102 (140596-138494), jiffies_till_next_fqs=1, root ->qsmask 0x0 [ 1705.994729] optee-xtest R running task 0 169 157 0x00000002

While OP-TEE is returning regulary to the kernel due to timer interrrupts, the OPTEE_SMC_FUNC_FOREIGN_INTR case does not contain an explicit rescheduling point. Add a might_sleep() to the RPC request case to ensure that the kernel can reschedule another task if OP-TEE requests RPC handling.

Signed-off-by: Rouven Czerwinski r.czerwinski@pengutronix.de

drivers/tee/optee/call.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c index aa942703ae65..13b0269a0abc 100644 --- a/drivers/tee/optee/call.c +++ b/drivers/tee/optee/call.c @@ -148,6 +148,7 @@ u32 optee_do_call_with_arg(struct tee_context *ctx, phys_addr_t parg) */ optee_cq_wait_for_completion(&optee->call_queue, &w); } else if (OPTEE_SMC_RETURN_IS_RPC(res.a0)) {

•                   might_sleep();
                    param.a0 = res.a0;
                    param.a1 = res.a1;
                    param.a2 = res.a2;
  

-- 2.20.1

Looks good. I'll pick this up and fix the spell errors in the commit message.

Thanks, Jens