[PATCH v3 0/7] scsi: ufs: core: Factor hba->outstanding_reqs helper and fix double completions

[Stanley Jhu <stanleyjhu@google.com>]

In Single Doorbell (SDB) mode, multiple completion and error handling
paths can race on the same transfer request when bits in
hba->outstanding_reqs are not claimed atomically with completing the
request. A stale bit in hba->outstanding_reqs lets a later poll or
reset complete the request again and unmap its DMA buffers twice.

Patch 1 removes a WARN_ONCE() in ufshcd_poll() whose condition is always
false.

Patch 2 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 3 uses the helper in ufshcd_clear_lu_cmds() to fix a double
completion during LU reset.

Patch 4 converts ufshcd_eh_timed_out() to the helper as a cleanup.

Patch 5 uses the helper return value in ufshcd_eh_timed_out() to prevent
releasing driver resources for a request already completed by another
context.

Patch 6 uses the helper in ufshcd_abort() to fix a double release in
the missing-interrupt path.

Patch 7 skips releasing reserved requests at the end of ufshcd_abort().

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

Tested on QEMU ARM64 UFS in SDB mode across LU reset, abort, and PM
timeout paths without double DMA unmaps.

Changes since v2:
- Move WARN_ONCE() removal to 1/7 and use __must_hold()/guard() (Bart).
- Add patch 5 to fix a double release in ufshcd_eh_timed_out().
- Add patch 6 to fix a double release in ufshcd_abort() (Bean, Bart).
- Add patch 7 to skip releasing reserved requests in ufshcd_abort().
- Link to v2: https://lore.kernel.org/r/20261017084403.875420-1-stanleyjhu@google.com

Stanley Jhu (7):
  scsi: ufs: core: Remove an always-false WARN_ONCE()
  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: Fix double release in ufshcd_eh_timed_out()
  scsi: ufs: core: Fix double release in ufshcd_abort()
  scsi: ufs: core: Do not release a reserved request in ufshcd_abort()

 drivers/ufs/core/ufshcd.c | 56 ++++++++++++++++++++++++---------------
 1 file changed, 35 insertions(+), 21 deletions(-)


base-commit: db8b4d2bf2d3e02b4ff78bbf69d00e11795840de
-- 
2.56.0.212.g129ede20d9-goog