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[v3,0/2] coresight: catu: Introduce refcount and spinlock for enabling/disabling

Message ID 20250408195922.770377-1-yabinc@google.com (mailing list archive)
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Series coresight: catu: Introduce refcount and spinlock for enabling/disabling | expand

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Yabin Cui April 8, 2025, 7:59 p.m. UTC 
Hi Coresight maintainers,

When tracing ETM data on multiple CPUs concurrently via the
perf interface, the CATU device is shared across different CPU
paths. This can lead to race conditions when multiple CPUs attempt
to enable or disable the CATU device simultaneously. This patchset
is to fix race conditions when enabling/disabling a CATU device.

Changes since v2:
- In catu_disable(), return 0 when refcnt > 0.
- Remove the patch checking enabled mode.
- Disable helpers at the places where a coresight device fails to
  enable.

Changes since v1:
- Use raw_spinlock_t and guard().
- Add a patch to check enabled mode.
- Add a patch to disable helpers when fails to enable a device.

Yabin Cui (2):
  coresight: catu: Introduce refcount and spinlock for
    enabling/disabling
  coresight: core: Disable helpers for devices that fail to enable

 drivers/hwtracing/coresight/coresight-catu.c | 25 +++++++++++++-------
 drivers/hwtracing/coresight/coresight-catu.h |  1 +
 drivers/hwtracing/coresight/coresight-core.c |  9 +++++--
 3 files changed, 25 insertions(+), 10 deletions(-)