coresight: sysfs: Validate CPU online status for per-CPU sources

The current SysFS flow first enables the links and sink, then rolls back
to disable them if the source fails to enable. This failure can occur if
the associated CPU is offline, which causes the SMP call to fail.

Validate whether the associated CPU is online for a per-CPU tracer.
If the CPU is offline, return -ENODEV and bail out.

Tested-by: James Clark <james.clark@linaro.org>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Tested-by: Jie Gan <jie.gan@oss.qualcomm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
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-v14-28-f88c4a3ecfe9@arm.com

diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
index 80b6b634a70d3cec98dfa3e5fd146cd254b96d6f..4b010f8bc4c08da31b3d295be6c37b6d941629d2 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-sysfs.c
@@ -168,6 +168,9 @@ static int coresight_validate_source_sysfs(struct coresight_device *csdev,
                return -EINVAL;
        }
 
+       if (coresight_is_percpu_source(csdev) && !cpu_online(csdev->cpu))
+               return -ENODEV;
+
        return 0;
 }