6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bart Van Assche [ Upstream commit 1373df88d53594a32534fd8960c51d1d09be8ecb ] Document the aspects of ufshcd_mcq_compl_all_cqes_lock() that are nontrivial in a comment block above this function. Signed-off-by: Bart Van Assche Reviewed-by: Peter Wang Link: https://patch.msgid.link/20260401202506.1445324-2-bvanassche@acm.org Signed-off-by: Martin K. Petersen Stable-dep-of: 375f3a5691dd ("scsi: ufs: core: Avoid unsafe MMIO reads in ufshcd_mcq_compl_all_cqes_lock()") Signed-off-by: Sasha Levin --- drivers/ufs/core/ufs-mcq.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c index 846d4c3eb3923..121601201fcd2 100644 --- a/drivers/ufs/core/ufs-mcq.c +++ b/drivers/ufs/core/ufs-mcq.c @@ -285,6 +285,14 @@ static void ufshcd_mcq_process_cqe(struct ufs_hba *hba, } } +/* + * This function is called from the UFS error handler with the UFS host + * controller disabled (HCE = 0). Reading host controller registers, e.g. the + * CQ tail pointer (CQTPy), may not be safe with the host controller disabled. + * Hence, iterate over all completion queue entries. This won't result in + * double completions because ufshcd_mcq_process_cqe() clears a CQE after it + * has been processed. + */ void ufshcd_mcq_compl_all_cqes_lock(struct ufs_hba *hba, struct ufs_hw_queue *hwq) { -- 2.53.0