rsxx: Moving pci_map_page to prevent overflow.

The pci_map_page function has been moved into our
issued workqueue to prevent an us running out of
mappable addresses on non-HWWD PCIe x8 slots. The
maximum amount that can possible be mapped at one
time now is: 255 dmas X 4 dma channels X 4096 Bytes.

Signed-off-by: Philip J Kelleher <pjk1939@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 28 insertions, 47 deletions

diff --git a/drivers/block/rsxx/core.c b/drivers/block/rsxx/core.c
index e740a650d546..a8de2eec6ff3 100644
--- a/drivers/block/rsxx/core.c
+++ b/drivers/block/rsxx/core.c
@@ -749,10 +749,6 @@ static pci_ers_result_t rsxx_slot_reset(struct pci_dev *dev)
 
         card->eeh_state = 0;
 
-        st = rsxx_eeh_remap_dmas(card);
-        if (st)
-                goto failed_remap_dmas;
-
         spin_lock_irqsave(&card->irq_lock, flags);
         if (card->n_targets & RSXX_MAX_TARGETS)
                 rsxx_enable_ier_and_isr(card, CR_INTR_ALL_G);
@@ -779,7 +775,6 @@ static pci_ers_result_t rsxx_slot_reset(struct pci_dev *dev)
         return PCI_ERS_RESULT_RECOVERED;
 
 failed_hw_buffers_init:
-failed_remap_dmas:
         for (i = 0; i < card->n_targets; i++) {
                 if (card->ctrl[i].status.buf)
                         pci_free_consistent(card->dev,
diff --git a/drivers/block/rsxx/dma.c b/drivers/block/rsxx/dma.c
index 71d1ca2a1444..34fd1018c8e5 100644
--- a/drivers/block/rsxx/dma.c
+++ b/drivers/block/rsxx/dma.c
@@ -397,6 +397,7 @@ static void rsxx_issue_dmas(struct rsxx_dma_ctrl *ctrl)
         int tag;
         int cmds_pending = 0;
         struct hw_cmd *hw_cmd_buf;
+        int dir;
 
         hw_cmd_buf = ctrl->cmd.buf;
 
@@ -433,6 +434,28 @@ static void rsxx_issue_dmas(struct rsxx_dma_ctrl *ctrl)
                         continue;
                 }
 
+                if (dma->cmd == HW_CMD_BLK_WRITE)
+                        dir = PCI_DMA_TODEVICE;
+                else
+                        dir = PCI_DMA_FROMDEVICE;
+
+                /*
+                 * The function pci_map_page is placed here because we can
+                 * only, by design, issue up to 255 commands to the hardware
+                 * at one time per DMA channel. So the maximum amount of mapped
+                 * memory would be 255 * 4 channels * 4096 Bytes which is less
+                 * than 2GB, the limit of a x8 Non-HWWD PCIe slot. This way the
+                 * pci_map_page function should never fail because of a
+                 * lack of mappable memory.
+                 */
+                dma->dma_addr = pci_map_page(ctrl->card->dev, dma->page,
+                                     dma->pg_off, dma->sub_page.cnt << 9, dir);
+                if (pci_dma_mapping_error(ctrl->card->dev, dma->dma_addr)) {
+                        push_tracker(ctrl->trackers, tag);
+                        rsxx_complete_dma(ctrl, dma, DMA_CANCELLED);
+                        continue;
+                }
+
                 set_tracker_dma(ctrl->trackers, tag, dma);
                 hw_cmd_buf[ctrl->cmd.idx].command  = dma->cmd;
                 hw_cmd_buf[ctrl->cmd.idx].tag      = tag;
@@ -629,14 +652,6 @@ static int rsxx_queue_dma(struct rsxx_cardinfo *card,
         if (!dma)
                 return -ENOMEM;
 
-        dma->dma_addr = pci_map_page(card->dev, page, pg_off, dma_len,
-                                     dir ? PCI_DMA_TODEVICE :
-                                     PCI_DMA_FROMDEVICE);
-        if (pci_dma_mapping_error(card->dev, dma->dma_addr)) {
-                kmem_cache_free(rsxx_dma_pool, dma);
-                return -ENOMEM;
-        }
-
         dma->cmd          = dir ? HW_CMD_BLK_WRITE : HW_CMD_BLK_READ;
         dma->laddr        = laddr;
         dma->sub_page.off = (dma_off >> 9);
@@ -1039,6 +1054,11 @@ int rsxx_eeh_save_issued_dmas(struct rsxx_cardinfo *card)
                         else
                                 card->ctrl[i].stats.reads_issued--;
 
+                        pci_unmap_page(card->dev, dma->dma_addr,
+                                       get_dma_size(dma),
+                                       dma->cmd == HW_CMD_BLK_WRITE ?
+                                       PCI_DMA_TODEVICE :
+                                       PCI_DMA_FROMDEVICE);
                         list_add_tail(&dma->list, &issued_dmas[i]);
                         push_tracker(card->ctrl[i].trackers, j);
                         cnt++;
@@ -1050,15 +1070,6 @@ int rsxx_eeh_save_issued_dmas(struct rsxx_cardinfo *card)
                 atomic_sub(cnt, &card->ctrl[i].stats.hw_q_depth);
                 card->ctrl[i].stats.sw_q_depth += cnt;
                 card->ctrl[i].e_cnt = 0;
-
-                list_for_each_entry(dma, &card->ctrl[i].queue, list) {
-                        if (!pci_dma_mapping_error(card->dev, dma->dma_addr))
-                                pci_unmap_page(card->dev, dma->dma_addr,
-                                               get_dma_size(dma),
-                                               dma->cmd == HW_CMD_BLK_WRITE ?
-                                               PCI_DMA_TODEVICE :
-                                               PCI_DMA_FROMDEVICE);
-                }
                 spin_unlock_bh(&card->ctrl[i].queue_lock);
         }
 
@@ -1067,31 +1078,6 @@ int rsxx_eeh_save_issued_dmas(struct rsxx_cardinfo *card)
         return 0;
 }
 
-int rsxx_eeh_remap_dmas(struct rsxx_cardinfo *card)
-{
-        struct rsxx_dma *dma;
-        int i;
-
-        for (i = 0; i < card->n_targets; i++) {
-                spin_lock_bh(&card->ctrl[i].queue_lock);
-                list_for_each_entry(dma, &card->ctrl[i].queue, list) {
-                        dma->dma_addr = pci_map_page(card->dev, dma->page,
-                                        dma->pg_off, get_dma_size(dma),
-                                        dma->cmd == HW_CMD_BLK_WRITE ?
-                                        PCI_DMA_TODEVICE :
-                                        PCI_DMA_FROMDEVICE);
-                        if (pci_dma_mapping_error(card->dev, dma->dma_addr)) {
-                                spin_unlock_bh(&card->ctrl[i].queue_lock);
-                                kmem_cache_free(rsxx_dma_pool, dma);
-                                return -ENOMEM;
-                        }
-                }
-                spin_unlock_bh(&card->ctrl[i].queue_lock);
-        }
-
-        return 0;
-}
-
 int rsxx_dma_init(void)
 {
         rsxx_dma_pool = KMEM_CACHE(rsxx_dma, SLAB_HWCACHE_ALIGN);