Hello arm-soc maintainers,
Please pull this small patch taking care of a rcu_sched trace in some corner cases when OP-TEE is invoked.
Thanks, Jens
The following changes since commit e71ba9452f0b5b2e8dc8aa5445198cd9214a6a62:
Linux 5.11-rc2 (2021-01-03 15:55:30 -0800)
are available in the Git repository at:
git://git.linaro.org/people/jens.wiklander/linux-tee.git tags/optee-rcu-sched-trace-for-v5.11
for you to fetch changes up to dcb3b06d9c34f33a249f65c08805461fb0c4325b:
tee: optee: replace might_sleep with cond_resched (2021-01-21 10:36:48 +0100)
---------------------------------------------------------------- Fix rcu_sched trace from OP-TEE invoke
Replaces might_sleep() with a conditional call to cond_resched() in order to avoid the rcu_sched trace in some corner cases.
---------------------------------------------------------------- Rouven Czerwinski (1): tee: optee: replace might_sleep with cond_resched
drivers/tee/optee/call.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
On Fri, Jan 22, 2021 at 8:42 AM Jens Wiklander jens.wiklander@linaro.org wrote:
for you to fetch changes up to dcb3b06d9c34f33a249f65c08805461fb0c4325b:
tee: optee: replace might_sleep with cond_resched (2021-01-21 10:36:48 +0100)
Fix rcu_sched trace from OP-TEE invoke
Replaces might_sleep() with a conditional call to cond_resched() in order to avoid the rcu_sched trace in some corner cases.
Hi Rouven,
The bugfix looks correct in the sense that it fixes the issue, but it took me a while to understand what you actually try to do here because of the unusual way it's written as
if (need_resched()) cond_resched();
which /looks/ like you are doing something fishy here. In the end I concluded that this was probably just a misunderstanding of what cond_resched() does.
Can you replace it with a normal
cond_resched()
without the second need_resched() check and make sure this still works? cond_resched() by definition performs the check to ensure that rescheduling is needed, so unless you want to explicitly hide the might_sleep() in it from being seen, it's better to call that.
Arnd
op-tee@lists.trustedfirmware.org
-
Arnd Bergmann -
Jens Wiklander