[PATCH v4 0/3] Coresight TMC-ETR: refactor the tmc-etr mode and some cleanups

[Junhao He <hejunhao3@h-partners.com>]

This patchset builds upon Yicong's previous patches [1].

Patch 2 introducing fix race issues found by using TMC-ETR.
Patch 1 & 3 introducing two cleanups found when debugging the issues.

[1] https://lore.kernel.org/linux-arm-kernel/20241202092419.11777-1-yangyicong@huawei.com/

---
Changes in v4:
 - a) Add comment at the context of set etr to sysfs mode.
 - b) Move the check on drvdata->read to the start of enable etr.
 - c) Add checks to prevent multiple sysfs processes from simultaneously
 competing to enable ETR.
 - d) Fix the issue with the guard used.
Link: https://lore.kernel.org/linux-arm-kernel/20250818080600.418425-1-hejunhao3@huawei.com/

---
Changes in v3:
 - Patches 1: Additional comment for tmc_drvdata::etr_mode. Update
 comment for tmc_drvdata::reading with Jonathan's Tag.
 - Patches 2: Replace scoped_guard with guard with Jonathan's Tag.
 - Patches 2: Fix spinlock to raw_spinlock, and refactor this code based
 on Leo's suggested solution.
 - Patches 3: change the size's type to ssize_t and use max_t to simplify
 the code with Leo's Tag.
Link: https://lore.kernel.org/linux-arm-kernel/20250620075412.952934-1-hejunhao3@huawei.com/

Changes in v2:
- Updated the commit of patch2.
- Rebase to v6.16-rc1

Junhao He (1):
  coresight: tmc: refactor the tmc-etr mode setting to avoid race
    conditions

Yicong Yang (2):
  coresight: tmc: Add missing doc including reading and etr_mode of
    struct tmc_drvdata
  coresight: tmc: Decouple the perf buffer allocation from sysfs mode

 .../hwtracing/coresight/coresight-tmc-etr.c   | 136 +++++++++---------
 drivers/hwtracing/coresight/coresight-tmc.h   |   2 +
 2 files changed, 66 insertions(+), 72 deletions(-)

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2.33.0