[PATCH v1 0/9] ring-buffer: Enable Clang context analysis

[Vincent Donnefort <vdonnefort@google.com>]

trace_buffer::subbuf_order has caused several recent resize races from
unguarded reads outside buffer->mutex. To prevent further regressions at
build time, enable Clang context analysis for the ring buffer and guard
subbuf_order with __guarded_by(&mutex).

  - Patches 1-3: Fix cpumask/hotplug races around buffer->buffers and
    trace_rb_cpu_prepare().
  - Patch 4: Fix a trace_marker resize race.
  - Patches 5-7: Remove subbuf_order reads from the write path.
  - Patches 8-9: Enable context analysis on ring_buffer.o and annotate
    subbuf_order with __guarded_by(&mutex).

Note: Patch 5 conflicts with the series removing absolute timestamps
[1], though both are independent on v7.4-rc1.

[1] https://lore.kernel.org/20261105202814.1350312-1-vdonnefort@google.com/

Vincent Donnefort (9):
  ring-buffer: Always read buffer->buffers after testing the cpumask
  ring-buffer: Drop cpus_read_lock() from ring_buffer_poll_remote()
  ring-buffer: Hold buffer->mutex in trace_rb_cpu_prepare()
  tracing: Cache ring_buffer_max_event_size() for trace_marker
  ring-buffer: Validate event length against rb_page_capacity()
  ring-buffer: Introduce rb_start_write() and rb_end_write()
  ring-buffer: Avoid reading buffer::subbuf_order on the write path
  ring-buffer: Enable context analysis
  ring-buffer: Annotate subbuf_order with __guarded_by(&mutex)

 kernel/trace/Makefile      |   2 +
 kernel/trace/ring_buffer.c | 350 ++++++++++++++++++++-----------------
 kernel/trace/trace.c       |   9 +-
 3 files changed, 193 insertions(+), 168 deletions(-)


base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
-- 
2.56.0.567.gdb80ae8cd5-goog