[PATCH v6 0/8] [PATCH v6 0/8] scsi_debug: Enable lock context analysis

[Bart Van Assche <bvanassche@acm.org>]

Hi Martin,

This patch series enables compiler-based lock context analysis for the
scsi_debug driver. Conditional locking is eliminated across command response
and error injection functions so that static analysis can verify lock
acquisitions and releases. Internal locking helper functions are annotated
with __acquires(),__releases(), __acquires_shared() and __releases_shared()
attributes. An error-path lock leak in resp_write_same() is fixed. Finally,
lock context analysis is enabled in drivers/scsi/Makefile.

Please consider this patch series for the next merge window.

Thanks,

Bart.

Changes compared to v5:
- Dropped a redundant zero-initialization of variable 'error' in corrupt_lbas()
  (patch 3/8).
- Changed 'ret == -1' checks to 'ret < 0' in resp_read_dt0() and
  resp_atomic_write() (John Garry; patches 4/8 and 6/8).
- Add Reviewed-by tags from Christoph Hellwig and John Garry to
  resp_read_dt0() (patch 4/8).
- In sdeb_meta_{read,write}_{,un}lock(), replace the inline comment
  '/*conditional locking*/' in __context_unsafe() with a comment explaining
  that these functions cannot be annotated with __acquire() or __release()
  without triggering undefined behavior (Christoph Hellwig; patch 7/8).

Changes compared to v4:
- Add a Reviewed-by tag from Christoph Hellwig to patch 6/8.
- Drop __context_unsafe() from sdeb_read_lock(), sdeb_read_unlock(),
  sdeb_write_lock(), and sdeb_write_unlock() in patch 7/8. Preserve the
  original if (sdebug_no_rwlock) conditional structure and annotate with
  __acquire_shared(), __release_shared(), __acquire(), and __release().
- Drop __context_unsafe() from sdeb_data_lock(), sdeb_data_unlock(),
  sdeb_data_sector_lock(), and sdeb_data_sector_unlock() in patch 7/8,
  and add explicit context capability transitions on the read paths.
- Retain __context_unsafe() exclusively for
  sdeb_meta_{read,write}_{,un}lock() to prevent undefined pointer
  arithmetic when sip is NULL under fake_rw.
- Update the commit description of patch 7/8 to reflect these changes.

Changes compared to v3:
- Add a new patch to split resp_atomic_write() and eliminate conditional
  locking in atomic write handling.
- Pass the LBP state boolean down into __resp_write_same(),
  __corrupt_lbas(), and __resp_write_dt0() to avoid repeated calls to
  scsi_debug_lbp().
- Drop unused function arguments from __resp_read_dt0_dix() and
  __resp_write_dt0_dix().
- Correct the return value descriptions in the header comments of
  __resp_read_dt0_dix() and __resp_write_dt0_dix().

Changes compared to v2:
- Move DIX/DIF verification into a helper function (__resp_read_dt0_dix())
  to reduce indentation.
- Remove unnecessary "else" branches after "return".
- Set the SCSI status code only if do_device_access() fails instead of
  unconditionally setting it to DID_ERROR << 16 beforehand.

Changes compared to v1:
- Fix an issue where the error code was clobbered in resp_write_same() and
  __resp_write_same() when fetch_to_dev_buffer() fails (John Garry and
  sashiko-bot).
- Fix return value handling in resp_read_dt0() and resp_write_dt0():
  previously a positive byte count returned by do_device_access() was
  incorrectly treated as a SCSI status code and returned to the caller.
  Now, pass the SCSI status via an output pointer and only trigger an error
  return on negative return values (sashiko-bot).
- Improve lock context annotations:
  * Annotate existing rwlock_t members (&sip->macc_data_lck,
    &sip->macc_sector_lck, &sip->macc_meta_lck) directly with __acquires /
    __releases instead of defining and embedding dummy context lock structs
    in struct sdeb_store_info.
  * Drop the unwarranted __context_unsafe() annotation from
    sdeb_data_read_lock().
  * Update the commit descriptions to match the code changes.

Bart Van Assche (8):
  scsi: scsi_debug: Fix a locking bug in resp_write_same()
  scsi: scsi_debug: Split resp_write_same()
  scsi: scsi_debug: Split corrupt_lbas()
  scsi: scsi_debug: Split resp_read_dt0()
  scsi: scsi_debug: Split resp_write_dt0()
  scsi: scsi_debug: Split resp_atomic_write()
  scsi: scsi_debug: Improve lock context annotations
  scsi: core: Enable lock context analysis for the scsi_debug driver

 drivers/scsi/Makefile     |   1 +
 drivers/scsi/scsi_debug.c | 454 ++++++++++++++++++++++++--------------
 2 files changed, 286 insertions(+), 169 deletions(-)