[PATCH v2 0/4] scsi: ufs: core: Factor hba->outstanding_reqs helper and fix double completion

[Stanley Jhu <stanleyjhu@google.com>]

In Single Doorbell (SDB) mode, ufshcd_clear_lu_cmds() clears a transfer
request slot in the controller and completes the request without
claiming its bit in hba->outstanding_reqs. A subsequent ufshcd_poll()
call sees the stale bit with its doorbell bit cleared and completes the
request a second time, causing a double DMA unmap.

Patch 1 adds __ufshcd_clear_outstanding_reqs() and
ufshcd_clear_outstanding_reqs() to share the bit-claim logic across
ufshcd_poll() and ufshcd_abort() with no functional change. Patch 2 uses
the new helper in ufshcd_clear_lu_cmds() to fix the SDB double
completion. Patch 3 uses the new helper in ufshcd_eh_timed_out(). It is
a follow-on cleanup and is not needed for the fix. Patch 4 removes a
WARN_ONCE() whose condition is always false.

This series is based on mkp/for-next (db8b4d2bf2d3).

Tested on QEMU ARM64 UFS in SDB and MCQ modes across LU reset, polled
and interrupt I/O, and task abort without double completion or DMA
unmap warnings.

Changes since v1:
- Add a helper for clearing hba->outstanding_reqs and use it in
  ufshcd_poll(), ufshcd_abort(), and ufshcd_clear_lu_cmds()
  (Bart Van Assche).
- Convert ufshcd_eh_timed_out() to use the new helper in patch 3.
- Remove an always-false WARN_ONCE() in patch 4.
- Link to v1: https://lore.kernel.org/r/20261016085403.1711740-1-stanleyjhu@google.com

Stanley Jhu (4):
  scsi: ufs: core: Add a helper for clearing hba->outstanding_reqs
  scsi: ufs: core: Fix double completion in ufshcd_clear_lu_cmds()
  scsi: ufs: core: Use ufshcd_clear_outstanding_reqs() in
    ufshcd_eh_timed_out()
  scsi: ufs: core: Remove an always-false WARN_ONCE()

 drivers/ufs/core/ufshcd.c | 55 +++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 20 deletions(-)


base-commit: db8b4d2bf2d3e02b4ff78bbf69d00e11795840de
-- 
2.56.0.176.g3575e65682-goog