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Date: Tue, 27 Aug 2013 17:59:24 -0500
From: "Philip J. Kelleher" <pjk1939@...ux.vnet.ibm.com>
To: axboe@...nel.dk
Cc: linux-kernel@...r.kernel.org, brking@...ux.vnet.ibm.com
Subject: [PATCH v2 2/2] rsxx: Moving pci_map_page to prevent overflow
From: Philip J Kelleher <pjk1939@...ux.vnet.ibm.com>
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@...ux.vnet.ibm.com>
-------------------------------------------------------------------------------
diff -uprN -X linux-block-vanilla/Documentation/dontdiff linux-block-vanilla/drivers/block/rsxx/core.c linux-block/drivers/block/rsxx/core.c
--- linux-block-vanilla/drivers/block/rsxx/core.c 2013-08-12 15:22:18.608859980 -0500
+++ linux-block/drivers/block/rsxx/core.c 2013-08-12 15:23:14.508859632 -0500
@@ -749,10 +749,6 @@ static pci_ers_result_t rsxx_slot_reset(
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(
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 -uprN -X linux-block-vanilla/Documentation/dontdiff linux-block-vanilla/drivers/block/rsxx/dma.c linux-block/drivers/block/rsxx/dma.c
--- linux-block-vanilla/drivers/block/rsxx/dma.c 2013-08-12 15:22:18.612863489 -0500
+++ linux-block/drivers/block/rsxx/dma.c 2013-08-12 15:23:22.158858765 -0500
@@ -397,6 +397,7 @@ static void rsxx_issue_dmas(struct rsxx_
int tag;
int cmds_pending = 0;
struct hw_cmd *hw_cmd_buf;
+ int dir;
hw_cmd_buf = ctrl->cmd.buf;
@@ -433,6 +434,27 @@ static void rsxx_issue_dmas(struct rsxx_
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)) {
+ kmem_cache_free(rsxx_dma_pool, dma);
+ return;
+ }
+
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 +651,6 @@ static int rsxx_queue_dma(struct rsxx_ca
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(ctrl->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 +1053,11 @@ int rsxx_eeh_save_issued_dmas(struct rsx
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 +1069,6 @@ int rsxx_eeh_save_issued_dmas(struct rsx
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(ctrl->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 +1077,6 @@ int rsxx_eeh_save_issued_dmas(struct rsx
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(ctrl->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);
--
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