kernel: bgmac: rework patch checking packet length

This bgmac patch was an attempt to fix/workaround bug reported in
https://dev.openwrt.org/ticket/7198 noticed on WNR3500L.
Patch assumed length reported by the hardware was 0 and was trying to
read it until getting a different value. This was actually the opposite.
Lenghts were some invalid & huge values that resulted in skb_over_panic.
For example:
skbuff: skb_over_panic: text:83b21074 len:57222 (...)
skbuff: skb_over_panic: text:87af1024 len:43226 (...)
skbuff: skb_over_panic: text:87af5024 len:8739 (...)

So instead of that not-working patch checking for 0, write a new one
checking for huge values. In case something like that happens, dump
hardware state and drop the packet.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@40424 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 24 insertions, 26 deletions

diff --git a/target/linux/generic/patches-3.10/775-bgmac-check-length-of-received-frame.patch b/target/linux/generic/patches-3.10/775-bgmac-check-length-of-received-frame.patch
index f708e7dcec..c3d63b65fa 100644
--- a/target/linux/generic/patches-3.10/775-bgmac-check-length-of-received-frame.patch
+++ b/target/linux/generic/patches-3.10/775-bgmac-check-length-of-received-frame.patch
@@ -9,33 +9,31 @@ Subject: [PATCH] bgmac: check length of received frame
 
 --- a/drivers/net/ethernet/broadcom/bgmac.c
 +++ b/drivers/net/ethernet/broadcom/bgmac.c
-@@ -349,6 +349,7 @@ static int bgmac_dma_rx_read(struct bgma
- 		struct sk_buff *skb = slot->skb;
- 		struct bgmac_rx_header *rx;
- 		u16 len, flags;
-+		int count;
- 
- 		/* Unmap buffer to make it accessible to the CPU */
- 		dma_sync_single_for_cpu(dma_dev, slot->dma_addr,
-@@ -357,6 +358,12 @@ static int bgmac_dma_rx_read(struct bgma
- 		/* Get info from the header */
- 		rx = (struct bgmac_rx_header *)skb->data;
- 		len = le16_to_cpu(rx->len);
-+		for (count = 0; count < 200; count++) {
-+			len = le16_to_cpu(rx->len);
-+			if (len)
-+				break;
-+			udelay(1);
-+		}
- 		flags = le16_to_cpu(rx->flags);
- 
- 		do {
-@@ -364,7 +371,7 @@ static int bgmac_dma_rx_read(struct bgma
+@@ -363,6 +363,27 @@ static int bgmac_dma_rx_read(struct bgma
+ 			dma_addr_t old_dma_addr = slot->dma_addr;
  			int err;
  
++			if (len > BGMAC_RX_MAX_FRAME_SIZE) {
++				struct bgmac_dma_desc *dma_desc = ring->cpu_base + ring->start;
++
++				bgmac_err(bgmac, "Hardware reported invalid packet length %d for slot %d!\n", len, ring->start);
++				bgmac_err(bgmac, "flags: 0x%04X\n", flags);
++				bgmac_err(bgmac, "ctl0: 0x%08X\tctl1: 0x%08X\n", le32_to_cpu(dma_desc->ctl0), le32_to_cpu(dma_desc->ctl1));
++
++				bgmac_err(bgmac, "   BGMAC_DMA_RX_CTL: 0x%08X\n", bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_CTL));
++				bgmac_err(bgmac, " BGMAC_DMA_RX_INDEX: 0x%08X\n", bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_INDEX));
++				bgmac_err(bgmac, "BGMAC_DMA_RX_RINGLO: 0x%08X\n", bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_RINGLO));
++				bgmac_err(bgmac, "BGMAC_DMA_RX_RINGHI: 0x%08X\n", bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_RINGHI));
++				bgmac_err(bgmac, "BGMAC_DMA_RX_STATUS: 0x%08X\n", bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_STATUS));
++				bgmac_err(bgmac, " BGMAC_DMA_RX_ERROR: 0x%08X\n", bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_ERROR));
++
++				dma_sync_single_for_device(dma_dev,
++							   slot->dma_addr,
++							   BGMAC_RX_BUF_SIZE,
++							   DMA_FROM_DEVICE);
++				break;
++			}
++
  			/* Check for poison and drop or pass the packet */
--			if (len == 0xdead && flags == 0xbeef) {
-+			if (!len || (len == 0xdead && flags == 0xbeef)) {
+ 			if (len == 0xdead && flags == 0xbeef) {
  				bgmac_err(bgmac, "Found poisoned packet at slot %d, DMA issue!\n",
- 					  ring->start);
- 				dma_sync_single_for_device(dma_dev,