[PATCH v3 0/2] scsi: ufs: core: Avoid redundant link recovery during system resume

[HOYOUNG SEO <hy50.seo@samsung.com>]

If a LINERESET is reported and the hibern8 exit fails during system
resume, both ufshcd_err_handler() and __ufshcd_wl_resume() call
ufshcd_link_recovery(), and the two recoveries are not serialized.

Patch 1 makes ufshcd_link_recovery() clear the saved errors like
ufshcd_reset_and_restore() does, so the error handler does not act on
errors that have already been recovered.

Patch 2 makes ufshcd_err_handler() wait for host_sem instead of
recovering the link early when the hba is system suspended.

Changes in v2:
- Add patch 1. As pointed out by the Sashiko review, saved_err and
  saved_uic_err are still set after the resume path recovered the link,
  so with v1 alone ufshcd_err_handler() would run a redundant recovery
  once host_sem is released.
- Patch 2: describe the race and the system/runtime PM difference in
  the commit message, and add a comment.

Changes in v3:
- Patch 2: reword the commit message only, no code change. The error
  handler does not always run a full recovery after a failed system
  resume; it stops according to ufshcd_err_handling_should_stop() (e.g.
  in UFSHCD_STATE_ERROR). Describe this behavior and refer to the commit
  that added the early link recovery (Sashiko review).
- Patch 1: no change.

HOYOUNG SEO (2):
  scsi: ufs: core: Clear saved errors in ufshcd_link_recovery
  scsi: ufs: core: add is_sys_suspended state before recovery

 drivers/ufs/core/ufshcd.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

-- 
2.34.1