[PATCH v3 0/2] drm/xe/guc: Prevent compiler read/write optimization breaks

[Jonathan Cavitt <jonathan.cavitt@intel.com>]

Use READ_ONCE and WRITE_ONCE when operating on ct->state and the
g2h_fence->done values to prevent the compiler from ignoring these
necessary operations.

v2: (Matt Brost)
- Add Fixes tags
- Add comments

v3:
- Split into multiple patches (Rodrigo Vivi)

v4:
- s/xe_guc_ct/guc (Michal W)
- Add comments with READ_ONCE and WRITE_ONCE updates
  (Rodrigo, Stuart, Dixit)
- Squash patches with same Fixes target
  (Rodrigo, Stuart, Dixit)
- Add partial comment justifying WRITE_ONCE in guc_ct_change_state
  before READ_ONCE in xe_guc_ct_enabled is added (Rodrigo Vivi)
  - Update above comment when adding READ_ONCE to xe_guc_ct_enabled
    (jcavitt)

v4: (Matt Brost)
- Squash patches operating on the same value together
- Remove unnecessary Fixes tags
- Add READ_ONCEs to pair with WRITE_ONCEs on g2h_fence->done

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Suggested-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>

Jonathan Cavitt (2):
  drm/xe/guc: READ/WRITE_ONCE g2h_fence->done
  drm/xe/guc: READ/WRITE_ONCE ct->state

 drivers/gpu/drm/xe/xe_guc_ct.c | 21 ++++++++++++++++-----
 drivers/gpu/drm/xe/xe_guc_ct.h |  6 ++++--
 2 files changed, 20 insertions(+), 7 deletions(-)

-- 
2.43.0