mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-07-22 06:57:30 -04:00
Code Issues Packages Projects Releases Wiki Activity

coresight: Save active path for system tracers

Browse Source 
This commit only set the path pointer for system tracers (e.g. STM) in
coresight_{enable|disable}_source().

Later changes will set the path pointer locally for per-CPU sources.
This is because the mode and path pointer must be set together, so that
they are observed atomically by the CPU PM notifier.

Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Tested-by: James Clark <james.clark@linaro.org>
Tested-by: Jie Gan <jie.gan@oss.qualcomm.com>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20260515-arm_coresight_path_power_management_improvement-v14-19-f88c4a3ecfe9@arm.com
This commit is contained in:
Leo Yan
2026-05-15 21:08:26 +01:00
committed by Suzuki K Poulose
parent a18e877b04
commit ac8eac9062
2 changed files with 24 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/hwtracing/coresight/coresight-core.c
View File

@@ -487,10 +487,28 @@ int coresight_enable_source(struct coresight_device *csdev,
struct perf_event *event, enum cs_mode mode,
struct coresight_path *path)
{
int ret;
if (!coresight_is_device_source(csdev))
return -EINVAL;
return source_ops(csdev)->enable(csdev, event, mode, path);
ret = source_ops(csdev)->enable(csdev, event, mode, path);
if (ret)
return ret;
/*
* Update the path pointer until after the source is enabled to avoid
* races where multiple paths attempt to enable the same source.
*
* Do not set the path pointer here for per-CPU sources; set it locally
* on the CPU instead. Otherwise, there is a window where the path is
* enabled but the pointer is not yet set, causing CPU PM notifiers to
* miss PM operations due to reading a NULL pointer.
*/
if (!coresight_is_percpu_source(csdev))
csdev->path = path;
return 0;
}
void coresight_disable_source(struct coresight_device *csdev, void *data)
@@ -498,6 +516,9 @@ void coresight_disable_source(struct coresight_device *csdev, void *data)
if (!coresight_is_device_source(csdev))
return;
if (!coresight_is_percpu_source(csdev))
csdev->path = NULL;
source_ops(csdev)->disable(csdev, data);
}
EXPORT_SYMBOL_GPL(coresight_disable_source);

2
include/linux/coresight.h
View File

@@ -257,6 +257,7 @@ struct coresight_trace_id_map {
* by @coresight_ops.
* @access: Device i/o access abstraction for this device.
* @dev: The device entity associated to this component.
* @path: Activated path pointer (only used for source device).
* @mode: The device mode, i.e sysFS, Perf or disabled. This is actually
* an 'enum cs_mode' but stored in an atomic type. Access is always
* through atomic APIs, ensuring SMP-safe synchronisation between
@@ -291,6 +292,7 @@ struct coresight_device {
const struct coresight_ops *ops;
struct csdev_access access;
struct device dev;
struct coresight_path *path;
atomic_t mode;
int refcnt;
int cpu;