✗ CI.checkpatch: warning for drm/xe: make CTX_TIME STAMP TOCTOU-safe and handle sentinels (rev9)

== Series Details ==

Series: drm/xe: make CTX_TIMESTAMP TOCTOU-safe and handle sentinels (rev9)
URL   : https://patchwork.freedesktop.org/series/168394/
State : warning

== Summary ==

+ KERNEL=/kernel
+ git clone https://gitlab.freedesktop.org/drm/maintainer-tools mt
Cloning into 'mt'...
warning: redirecting to https://gitlab.freedesktop.org/drm/maintainer-tools.git/
+ git -C mt rev-list -n1 origin/master
061140b9bc586ae7f40abc1249c97e1cc72d1b9d
+ cd /kernel
+ git config --global --add safe.directory /kernel
+ git log -n1
commit a45eca1ca26a1d66693bd0518f6cc179fdb7563f
Author: Gajendra Uttamchand <[email protected]>
Date:   Fri Jul 31 04:00:08 2026 +0000

    drm/xe/lrc: Fix ABA race on engine migration in context timestamp read
    
    xe_lrc_context_timestamp() reads the engine id once via
    xe_lrc_engine_id(lrc) and uses it to fetch the live CTX_TIMESTAMP MMIO
    register, then re-checks the LRC-stored value to detect whether the
    context switched out while the MMIO read was in flight. That check
    only confirms the context is (still/again) active - it does not
    confirm it is active on the *same* engine the MMIO read targeted.
    
    If the context is saved and restored onto a different engine between
    the initial engine id read and the final activity check, the
    CONTEXT_ACTIVE sentinel will be observed again (now for the new
    engine), and the stale MMIO value read from the old, now-unrelated
    engine is returned as if it were valid.
    
    Pin the engine id used for the MMIO read and re-validate it against
    the current engine id after the final activity check. If the engine
    changed, retry the whole read (bounded by a small retry count) instead
    of trusting a timestamp sampled from an unrelated context, falling
    back to the last cached value if the context keeps migrating.
    
    Assisted-by: GitHub-Copilot:claude-sonnet-5
    Signed-off-by: Gajendra Uttamchand <[email protected]>
+ /mt/dim checkpatch 374d957e1908042c257b8c239974317bb93b83dc drm-intel
09b881e5fd4b drm/xe/lrc: document sentinel and make CTX_TIMESTAMP read TOCTOU-safe
da6cf8082518 drm/xe/lrc: Fix torn read of CTX_TIMESTAMP from LRC
-:54: WARNING:MEMORY_BARRIER: memory barrier without comment
#54: FILE: drivers/gpu/drm/xe/xe_lrc.c:892:
+		smp_rmb();

total: 0 errors, 1 warnings, 0 checks, 37 lines checked
a45eca1ca26a drm/xe/lrc: Fix ABA race on engine migration in context timestamp read