rsxx: Disallow discards from being unmapped.

This patch fixes a bug in which discards were always
calling pci_unmap_page. Discards should never call the
pci_unmap_page function call because they are never mapped.

This caused a race condition on PowerPC systems when issuing
discards, writes, and reads all at the same time. The
pci_map_page function would eventually map logical address
0 for a read or write. Discards are always assigned a DMA
address of 0 because they are never mapped. So if
pci_map_page mapped address 0 for a DMA and a discard was
"unmapped" then the address would be freed and would cause
an EEH event to occur when Hardware accesses the address.

This was injected/uncovered in commit:
b347f9cf0bc8d42ee95ba1d3837fd93045ab336b

The pci_dma_mapping_error function declares -1 a DMA_ERROR
not 0 like initially thought So before we would never unmap
discards because they were considered NULL.

This patch should fall on top of commit id:
fc1967bb08a6184ed44ef990e1dd4389901b809c

Also, the driver version is being up dated.

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

2 files changed, 17 insertions, 12 deletions

diff --git a/drivers/block/rsxx/dma.c b/drivers/block/rsxx/dma.c
index 4103601ae675..fc88ba3e1bd2 100644
--- a/drivers/block/rsxx/dma.c
+++ b/drivers/block/rsxx/dma.c
@@ -223,12 +223,14 @@ static void dma_intr_coal_auto_tune(struct rsxx_cardinfo *card)
 /*----------------- RSXX DMA Handling -------------------*/
 static void rsxx_free_dma(struct rsxx_dma_ctrl *ctrl, struct rsxx_dma *dma)
 {
-        if (!pci_dma_mapping_error(ctrl->card->dev, dma->dma_addr)) {
-                pci_unmap_page(ctrl->card->dev, dma->dma_addr,
-                               get_dma_size(dma),
-                               dma->cmd == HW_CMD_BLK_WRITE ?
-                                           PCI_DMA_TODEVICE :
-                                           PCI_DMA_FROMDEVICE);
+        if (dma->cmd != HW_CMD_BLK_DISCARD) {
+                if (!pci_dma_mapping_error(ctrl->card->dev, dma->dma_addr)) {
+                        pci_unmap_page(ctrl->card->dev, dma->dma_addr,
+                                       get_dma_size(dma),
+                                       dma->cmd == HW_CMD_BLK_WRITE ?
+                                                   PCI_DMA_TODEVICE :
+                                                   PCI_DMA_FROMDEVICE);
+                }
         }
 
         kmem_cache_free(rsxx_dma_pool, dma);
@@ -1057,11 +1059,14 @@ 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);
+                        if (dma->cmd != HW_CMD_BLK_DISCARD) {
+                                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++;
diff --git a/drivers/block/rsxx/rsxx_priv.h b/drivers/block/rsxx/rsxx_priv.h
index 913740e53d31..23fa05630fef 100644
--- a/drivers/block/rsxx/rsxx_priv.h
+++ b/drivers/block/rsxx/rsxx_priv.h
@@ -52,7 +52,7 @@ struct proc_cmd;
 #define RS70_PCI_REV_SUPPORTED  4
 
 #define DRIVER_NAME "rsxx"
-#define DRIVER_VERSION "4.0.1.2498"
+#define DRIVER_VERSION "4.0.2.2510"
 
 /* Block size is 4096 */
 #define RSXX_HW_BLK_SHIFT               12