RE: [RFC PATCH 4/5] scsi: ufs: L2P map management for HPB read

Avri Altman
2020-06-06T18:26:36Z

>
> A pinned region is a pre-set regions on the UFS device that is always
> activate-state and
This sentence got cut off

>
> The data structure for map data request and L2P map uses mempool API,
> minimizing allocation overhead while avoiding static allocation.

Maybe one or two more sentences to explain the L2P framework:
Each hpb lun maintains 2 "to-do" lists:
- hpb->lh_inact_rgn - regions to be inactivated, and
- hpb->lh_act_srgn - subregions to be activated
Those lists are being checked on every resume and completion interrupt.

>
> Signed-off-by: Daejun Park <daejun7.park@samsung.com>
> ---
> + for (i = 0; i < hpb->pages_per_srgn; i++) {
> + mctx->m_page[i] = mempool_alloc(ufshpb_drv.ufshpb_page_pool,
> + GFP_KERNEL);
> + memset(page_address(mctx->m_page[i]), 0, PAGE_SIZE);
Better move this memset after if (!mctx->m_page[i]).
And maybe use clear_page instead?

> + if (!mctx->m_page[i]) {
> + for (j = 0; j < i; j++)
> + mempool_free(mctx->m_page[j],
> + ufshpb_drv.ufshpb_page_pool);
> + goto release_ppn_dirty;
> + }

> +static inline int ufshpb_add_region(struct ufshpb_lu *hpb,
> + struct ufshpb_region *rgn)
> +{
Maybe better describe what this function does - ufshpb_get_rgn_map_ctx ?

> +
> +static int ufshpb_evict_region(struct ufshpb_lu *hpb, struct ufshpb_region
> *rgn)
> +{
> + unsigned long flags;
> + int ret = 0;
> +
> + spin_lock_irqsave(&hpb->hpb_state_lock, flags);
> + if (rgn->rgn_state == HPB_RGN_PINNED) {
> + dev_warn(&hpb->hpb_lu_dev,
> + "pinned region cannot drop-out. region %d\n",
> + rgn->rgn_idx);
> + goto out;
> + }
> +
> + if (!list_empty(&rgn->list_lru_rgn)) {
> + if (ufshpb_check_issue_state_srgns(hpb, rgn)) {
So if one of its subregions has inflight map request - you add it to the "starved" list?
Why call it starved?

> +static int ufshpb_issue_map_req(struct ufshpb_lu *hpb,
> + struct ufshpb_region *rgn,
> + struct ufshpb_subregion *srgn)
> +{
> + struct ufshpb_req *map_req;
> + unsigned long flags;
> + int ret = 0;
> +
> + spin_lock_irqsave(&hpb->hpb_state_lock, flags);
> + /*
> + * Since the region state change occurs only in the hpb task-work,
> + * the state of the region cannot HPB_RGN_INACTIVE at this point.
> + * The region state must be changed in the hpb task-work
I think that you called this worker map_work?

> + spin_unlock_irqrestore(&hpb->hpb_state_lock, flags);
> + ret = ufshpb_add_region(hpb, rgn);
If this is not an active region,
Although the device indicated to activate a specific subregion,
You are activating all the subregions of that region.
You should elaborate on that in your commit log,
and explain why this is the correct activation course.

> + /*
> + * If the active region and the inactive region are the same,
> + * we will inactivate this region.
> + * The device could check this (region inactivated) and
> + * will response the proper active region information
> + */
> + spin_lock(&hpb->rsp_list_lock);
> + for (i = 0; i < rsp_field->active_rgn_cnt; i++) {
> + rgn_idx =
> + be16_to_cpu(rsp_field->hpb_active_field[i].active_rgn);
> + srgn_idx =
> + be16_to_cpu(rsp_field->hpb_active_field[i].active_srgn);
get_unaligned instead of be16_to_cpu ?

> +
> + dev_dbg(&hpb->hpb_lu_dev, "activate(%d) region %d - %d\n",
> + i, rgn_idx, srgn_idx);
> + ufshpb_update_active_info(hpb, rgn_idx, srgn_idx);
> + atomic_inc(&hpb->stats.rb_active_cnt);
> + }
> +
> + for (i = 0; i < rsp_field->inactive_rgn_cnt; i++) {
> + rgn_idx = be16_to_cpu(rsp_field->hpb_inactive_field[i]);
> + dev_dbg(&hpb->hpb_lu_dev, "inactivate(%d) region %d\n",
> + i, rgn_idx);
> + ufshpb_update_inactive_info(hpb, rgn_idx);
> + atomic_inc(&hpb->stats.rb_inactive_cnt);
> + }
> + spin_unlock(&hpb->rsp_list_lock);
> +
> + dev_dbg(&hpb->hpb_lu_dev, "Noti: #ACT %u #INACT %u\n",
> + rsp_field->active_rgn_cnt, rsp_field->inactive_rgn_cnt);
> +
> + queue_work(ufshpb_drv.ufshpb_wq, &hpb->map_work);
> +}
> +
> +/* routine : isr (ufs) */
> +static void ufshpb_rsp_upiu(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
> +{
> + struct ufshpb_lu *hpb;
> + struct ufshpb_rsp_field *rsp_field;
> + int data_seg_len, ret;
> +
> + data_seg_len = be32_to_cpu(lrbp->ucd_rsp_ptr->header.dword_2)
> + & MASK_RSP_UPIU_DATA_SEG_LEN;
get_unaligned instead of be32_to_cpu ?

> +
> + if (!data_seg_len) {
data_seg_len should be DEV_DATA_SEG_LEN, and you should also check HPB_UPDATE_ALERT,
which you might want to do here and not in ufshpb_may_field_valid

> + if (!ufshpb_is_general_lun(lrbp->lun))
> + return;
> +
> + hpb = ufshpb_get_hpb_data(lrbp->cmd);
> + ret = ufshpb_lu_get(hpb);
> + if (ret)
> + return;
> +
> + if (!ufshpb_is_empty_rsp_lists(hpb))
> + queue_work(ufshpb_drv.ufshpb_wq, &hpb->map_work);
> +
> + goto put_hpb;
> + }
> +
> + rsp_field = ufshpb_get_hpb_rsp(lrbp);
> + if (ufshpb_may_field_valid(hba, lrbp, rsp_field))
> + return;
> +
> + hpb = ufshpb_get_hpb_data(lrbp->cmd);
> + ret = ufshpb_lu_get(hpb);
> + if (ret)
> + return;
> +
> + atomic_inc(&hpb->stats.rb_noti_cnt);
> +
> + switch (rsp_field->hpb_type) {
> + case HPB_RSP_REQ_REGION_UPDATE:
> + WARN_ON(data_seg_len != DEV_DATA_SEG_LEN);
> + ufshpb_rsp_req_region_update(hpb, rsp_field);
> + break;
What about hpb dev reset - oper 0x2?

> + default:
> + dev_notice(&hpb->hpb_lu_dev, "hpb_type is not available: %d\n",
> + rsp_field->hpb_type);
> + break;
> + }
> +put_hpb:
> + ufshpb_lu_put(hpb);
> +}
> +

> +static void ufshpb_add_active_list(struct ufshpb_lu *hpb,
> + struct ufshpb_region *rgn,
> + struct ufshpb_subregion *srgn)
> +{
> + if (!list_empty(&rgn->list_inact_rgn))
> + return;
> +
> + if (!list_empty(&srgn->list_act_srgn)) {
> + list_move(&srgn->list_act_srgn, &hpb->lh_act_srgn);
Why is this needed?
Why updating this subregion position?

> + return;
> + }
> +
> + list_add(&srgn->list_act_srgn, &hpb->lh_act_srgn);
> +}

> @@ -195,8 +1047,15 @@ static int ufshpb_alloc_region_tbl(struct ufs_hba
> *hba, struct ufshpb_lu *hpb)
> release_srgn_table:
> for (i = 0; i < rgn_idx; i++) {
> rgn = rgn_table + i;
> - if (rgn->srgn_tbl)
> + if (rgn->srgn_tbl) {
> + for (srgn_idx = 0; srgn_idx < rgn->srgn_cnt;
> + srgn_idx++) {
> + srgn = rgn->srgn_tbl + srgn_idx;
> + if (srgn->mctx)
How is it even possible that on init there is an active subregion?
ufshpb_init_pinned_active_region does its own cleanup.

> + hpb->m_page_cache = kmem_cache_create("ufshpb_m_page_cache",
> + sizeof(struct page *) * hpb->pages_per_srgn,
> + 0, 0, NULL);
What is the advantage in using an array of page pointers,
Instead of a single pointer to pages_per_srgn?

> @@ -398,6 +1326,9 @@ static void ufshpb_resume(struct ufs_hba *hba)
>
> dev_info(&hpb->hpb_lu_dev, "ufshpb resume");
> ufshpb_set_state(hpb, HPB_PRESENT);
> + if (!ufshpb_is_empty_rsp_lists(hpb))
> + queue_work(ufshpb_drv.ufshpb_wq, &hpb->map_work);
Ahha - so you are using the ufs driver pm flows to poll your work queue.
Why device recommendations isn't enough?

> +
> ufshpb_lu_put(hpb);
> }
> }

Thanks,
Avri