[PATCH v6 00/13] fix several inconsistencies with sysfs configuration in etmX

Yeoreum Yun
2026-04-22T13:22:22Z

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.

Also, This patch set includes some small fixes:
- missing trace id release in etm4x.
- underflow issue for nrseqstate.
- wrong check in etm4x_sspcicrn_present().
- missing call of cscfg_csdev_disable_active_config()

This patch based on v7.0

Patch History
=============
from v5 to v6:
- fix missing of calling cscfg_csdev_disable_active_config()
- add rb & fixes tags.
- add ss_status field in etm4x_drvdata to expose STATUS and PENDING bits.
- https://lore.kernel.org/all/20260415165528.3369607-1-yeoreum.yun@arm.com/

from v4 to v5:
- add rb-tag.
- fix underflow issue for nrseqstate.
- fix wrong check in etm4_sspcicrn_present().
- remove redundant fields on etmv4_save_state.
- rename caps->ss_status to ss_cmp.
- fix wrong location of etm4_release_trace_id.
- https://lore.kernel.org/all/20260413142003.3549310-1-yeoreum.yun@arm.com/

from v3 to v4:
- change etm_drvdata->spinlock type to raw_spin_lock_t
- remove redundant call etmX_enable_hw() with starting_cpu() callsback.
- fix missing trace id release.
- add missing docs.
- https://lore.kernel.org/all/20260412175506.412301-1-yeoreum.yun@arm.com/

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 (13):
coresight: etm4x: fix wrong check of etm4x_sspcicrn_present()
coresight: etm4x: fix underflow for nrseqstate
coresight: etm4x: introduce struct etm4_caps
coresight: etm4x: exclude ss_status from drvdata->config
coresight: etm4x: remove redundant fields in etmv4_save_state
coresight: etm4x: fix leaked trace id
coresight: etm4x: fix inconsistencies with sysfs configuration
coresight: etm4x: remove redundant call etm4_enable_hw() with hotplug
coresight: etm4x: missing cscfg_csdev_disable_active_config() in perf
enable
coresight: etm3x: change drvdata->spinlock type to raw_spin_lock_t
coresight: etm3x: introduce struct etm_caps
coresight: etm3x: fix inconsistencies with sysfs configuration
coresight: etm3x: remove redundant call etm_enable_hw() with hotplug

drivers/hwtracing/coresight/coresight-etm.h | 46 ++-
.../coresight/coresight-etm3x-core.c | 101 ++---
.../coresight/coresight-etm3x-sysfs.c | 159 +++----
.../hwtracing/coresight/coresight-etm4x-cfg.c | 3 +-
.../coresight/coresight-etm4x-core.c | 388 ++++++++++--------
.../coresight/coresight-etm4x-sysfs.c | 202 +++++----
drivers/hwtracing/coresight/coresight-etm4x.h | 190 +++++----
7 files changed, 606 insertions(+), 483 deletions(-)

base-commit: 028ef9c96e96197026887c0f092424679298aae8