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-c97ec1aa4b7...

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.