cassini: Use page_address() instead of kmap_atomic()

Pages for Rx buffers are allocated in cas_page_alloc() using either
GFP_ATOMIC or GFP_KERNEL. Memory allocated with GFP_KERNEL/GFP_ATOMIC can't
come from highmem and so there's no need to kmap() them. Just use
page_address() instead. This makes the variable 'addr' unnecessary, so
remove it too.

Note that kmap_atomic() disables preemption and page-fault processing,
but page_address() doesn't. When removing uses of kmap_atomic(), one has to
check if the code being executed between the map/unmap implicitly depends
on page-faults and/or preemption being disabled. If yes, then code to
disable page-faults and/or preemption should also be added for functional
correctness. That however doesn't appear to be the case here, so just
page_address() is used.

I don't have hardware, so this change has only been compile tested.

Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/sun/cassini.c b/drivers/net/ethernet/sun/cassini.c
index 0aca193..2f66cfc 100644 (file)
--- a/drivers/net/ethernet/sun/cassini.c
+++ b/drivers/net/ethernet/sun/cassini.c
@@ -1915,7 +1915,7 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
        int off, swivel = RX_SWIVEL_OFF_VAL;
        struct cas_page *page;
        struct sk_buff *skb;
-       void *addr, *crcaddr;
+       void *crcaddr;
        __sum16 csum;
        char *p;
 
@@ -1936,7 +1936,7 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
        skb_reserve(skb, swivel);
 
        p = skb->data;
-       addr = crcaddr = NULL;
+       crcaddr = NULL;
        if (hlen) { /* always copy header pages */
                i = CAS_VAL(RX_COMP2_HDR_INDEX, words[1]);
                page = cp->rx_pages[CAS_VAL(RX_INDEX_RING, i)][CAS_VAL(RX_INDEX_NUM, i)];
@@ -1948,12 +1948,10 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
                        i += cp->crc_size;
                dma_sync_single_for_cpu(&cp->pdev->dev, page->dma_addr + off,
                                        i, DMA_FROM_DEVICE);
-               addr = cas_page_map(page->buffer);
-               memcpy(p, addr + off, i);
+               memcpy(p, page_address(page->buffer) + off, i);
                dma_sync_single_for_device(&cp->pdev->dev,
                                           page->dma_addr + off, i,
                                           DMA_FROM_DEVICE);
-               cas_page_unmap(addr);
                RX_USED_ADD(page, 0x100);
                p += hlen;
                swivel = 0;
@@ -1984,12 +1982,11 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
                /* make sure we always copy a header */
                swivel = 0;
                if (p == (char *) skb->data) { /* not split */
-                       addr = cas_page_map(page->buffer);
-                       memcpy(p, addr + off, RX_COPY_MIN);
+                       memcpy(p, page_address(page->buffer) + off,
+                              RX_COPY_MIN);
                        dma_sync_single_for_device(&cp->pdev->dev,
                                                   page->dma_addr + off, i,
                                                   DMA_FROM_DEVICE);
-                       cas_page_unmap(addr);
                        off += RX_COPY_MIN;
                        swivel = RX_COPY_MIN;
                        RX_USED_ADD(page, cp->mtu_stride);
@@ -2036,10 +2033,8 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
                        RX_USED_ADD(page, hlen + cp->crc_size);
                }
 
-               if (cp->crc_size) {
-                       addr = cas_page_map(page->buffer);
-                       crcaddr  = addr + off + hlen;
-               }
+               if (cp->crc_size)
+                       crcaddr = page_address(page->buffer) + off + hlen;
 
        } else {
                /* copying packet */
@@ -2061,12 +2056,10 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
                        i += cp->crc_size;
                dma_sync_single_for_cpu(&cp->pdev->dev, page->dma_addr + off,
                                        i, DMA_FROM_DEVICE);
-               addr = cas_page_map(page->buffer);
-               memcpy(p, addr + off, i);
+               memcpy(p, page_address(page->buffer) + off, i);
                dma_sync_single_for_device(&cp->pdev->dev,
                                           page->dma_addr + off, i,
                                           DMA_FROM_DEVICE);
-               cas_page_unmap(addr);
                if (p == (char *) skb->data) /* not split */
                        RX_USED_ADD(page, cp->mtu_stride);
                else
@@ -2081,20 +2074,17 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
                                                page->dma_addr,
                                                dlen + cp->crc_size,
                                                DMA_FROM_DEVICE);
-                       addr = cas_page_map(page->buffer);
-                       memcpy(p, addr, dlen + cp->crc_size);
+                       memcpy(p, page_address(page->buffer), dlen + cp->crc_size);
                        dma_sync_single_for_device(&cp->pdev->dev,
                                                   page->dma_addr,
                                                   dlen + cp->crc_size,
                                                   DMA_FROM_DEVICE);
-                       cas_page_unmap(addr);
                        RX_USED_ADD(page, dlen + cp->crc_size);
                }
 end_copy_pkt:
-               if (cp->crc_size) {
-                       addr    = NULL;
+               if (cp->crc_size)
                        crcaddr = skb->data + alloclen;
-               }
+
                skb_put(skb, alloclen);
        }
 
@@ -2103,8 +2093,6 @@ end_copy_pkt:
                /* checksum includes FCS. strip it out. */
                csum = csum_fold(csum_partial(crcaddr, cp->crc_size,
                                              csum_unfold(csum)));
-               if (addr)
-                       cas_page_unmap(addr);
        }
        skb->protocol = eth_type_trans(skb, cp->dev);
        if (skb->protocol == htons(ETH_P_IP)) {