[PATCH v3 0/5] fix inconsistencies with sysfs configuration in etmX

Yeoreum Yun
2026-04-12T17:55:21Z

The current ETMx configuration via sysfs can lead to the following
inconsistencies:

- If a configuration is modified via sysfs while a perf session is
active, the running configuration may differ between before
a sched-out and after a subsequent sched-in.

- If a perf session and sysfs session tries to enable concurrently,
configuration from configfs could be corrupted (etm4).

- There is chance to corrupt drvdata->config if perf session tries
to enabled among handling cscfg_csdev_disable_active_config()
in etm4_disable_sysfs() (etm4).

To resolve these inconsistencies, the configuration should be separated into:

- active_config, which is applied configuration for the current session
- config, which stores the settings configured via sysfs.

and apply configuration from configfs after taking a mode.

This patch based on v7.0-rc7

Patch History
=============
from v2 to v3:
- fix build error for etm3x.
- fix checkpatch warning.
- https://lore.kernel.org/all/20260410074310.2693385-1-yeoreum.yun@arm.com/

from v1 to v2
- rebased to v7.0-rc7.
- introduce etmX_caps structure to save etmX's capabilities.
- remove ss_status from etmv4_config.
- modify active_config after taking a mode (perf/sysfs).
- https://lore.kernel.org/all/20260317181705.2456271-1-yeoreum.yun@arm.com/

Yeoreum Yun (5):
coresight: etm4x: introduce struct etm4_caps
coresight: etm4x: exclude ss_status from drvdata->config
coresight: etm4x: fix inconsistencies with sysfs configration
coresight: etm3x: introduce struct etm_caps
coresight: etm3x: fix inconsistencies with sysfs configration

drivers/hwtracing/coresight/coresight-etm.h | 44 ++-
.../coresight/coresight-etm3x-core.c | 59 ++--
.../coresight/coresight-etm3x-sysfs.c | 29 +-
.../hwtracing/coresight/coresight-etm4x-cfg.c | 3 +-
.../coresight/coresight-etm4x-core.c | 322 ++++++++++--------
.../coresight/coresight-etm4x-sysfs.c | 197 ++++++-----
drivers/hwtracing/coresight/coresight-etm4x.h | 180 +++++-----
7 files changed, 465 insertions(+), 369 deletions(-)

base-commit: 591cd656a1bf5ea94a222af5ef2ee76df029c1d2