On 25/11/2024 9:48 am, Yeoreum Yun wrote:
> In some coresight drivers, drvdata->spinlock can be held during __schedule()
> by perf_event_task_sched_out()/in().
>
> Since drvdata->spinlock type is spinlock_t and
> perf_event_task_sched_out()/in() is called after acquiring rq_lock,
> which is raw_spinlock_t (an unsleepable lock),
> this poses an issue in PREEMPT_RT kernel where spinlock_t is sleepable.
>
> To address this,change type drvdata->spinlock in some coresight drivers,
> which can be called by perf_event_task_sched_out()/in(),
> from spinlock_t to raw_spinlock_t.
>
> Levi Yun (9):
> coresight: change coresight_device lock type to raw_spinlock_t
> coresight-etm4x: change etmv4_drvdata spinlock type to raw_spinlock_t
> coresight: change coresight_trace_id_map's lock type to raw_spinlock_t
> coresight-cti: change cti_drvdata spinlock's type to raw_spinlock_t
> coresight-etb10: change etb_drvdata spinlock's type to raw_spinlock_t
> coresight-funnel: change funnel_drvdata spinlock's type to
> raw_spinlock_t
> coresight-replicator: change replicator_drvdata spinlock's type to
> raw_spinlock_t
> coresight-tmc: change tmc_drvdata spinlock's type to raw_spinlock_t
> coresight/ultrasoc: change cti_drvdata spinlock's type to
> raw_spinlock_t
>
> .../hwtracing/coresight/coresight-config.c | 21 +-
> .../hwtracing/coresight/coresight-config.h | 2 +-
> drivers/hwtracing/coresight/coresight-core.c | 2 +-
> .../hwtracing/coresight/coresight-cti-core.c | 65 +-
> .../hwtracing/coresight/coresight-cti-sysfs.c | 135 +++--
> drivers/hwtracing/coresight/coresight-cti.h | 2 +-
> drivers/hwtracing/coresight/coresight-etb10.c | 62 +-
> .../coresight/coresight-etm4x-core.c | 71 ++-
> .../coresight/coresight-etm4x-sysfs.c | 566 +++++++++---------
> drivers/hwtracing/coresight/coresight-etm4x.h | 2 +-
> .../hwtracing/coresight/coresight-funnel.c | 34 +-
> .../coresight/coresight-replicator.c | 36 +-
> .../hwtracing/coresight/coresight-syscfg.c | 75 ++-
> .../hwtracing/coresight/coresight-tmc-core.c | 9 +-
> .../hwtracing/coresight/coresight-tmc-etf.c | 195 +++---
> .../hwtracing/coresight/coresight-tmc-etr.c | 199 +++---
> drivers/hwtracing/coresight/coresight-tmc.h | 2 +-
> .../hwtracing/coresight/coresight-trace-id.c | 93 ++-
> drivers/hwtracing/coresight/ultrasoc-smb.c | 12 +-
> drivers/hwtracing/coresight/ultrasoc-smb.h | 2 +-
> include/linux/coresight.h | 4 +-
> 21 files changed, 751 insertions(+), 838 deletions(-)
>
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>
Reviewed-by: James Clark <james.clark@linaro.org>
Somewhat related to this change, but not something that needs to be done
now:
All of the spinlocks for the syfs store/read functions don't need to be
raw spinlocks, or spinlocks at all. They're never called from the
scheduling code and can be locked by coresight_mutex instead.
coresight_mutex is held on the sysfs enable/disable path when those
values are actually used.
Same point as here:
https://lore.kernel.org/linux-arm-kernel/9a637e74-d81d-405c-bad0-c97ec1aa4b77@linaro.org/
Probably needs a review of which values in each device might be shared
between perf mode and sysfs mode when they shouldn't be, as there was
one in the link above.
I thought the only thing shared between sysfs and perf should be the
'mode' which is taken with a compare and swap without locking anyway.