b44: GFP_DMA skb should not escape from driver (a58c891a) · Commits · 戴 / test

b44 chip has some hardware limitations, that need GFP_DMA bounce buffers in some situations. In order to not deplete DMA zone, we should keep allocated GFP_DMA skb only for driver use. At rx time, we copy such skb to newly allocated skb, reusing existing copybreak infrastructure. On machines with low amount of memory, all skb meet the hardware limitation, so no copy is needed. We detect this situation using a new device flag, set to one if one GFP_DMA skb was ever allocated by b44_alloc_rx_skb(). Previously allocated skb, even outside from DMA zone will then be recycled, to have minimal impact on DMA zone use. Signed-off-by:

Eric Dumazet <dada1@cosmosbay.com> Tested-by:

Ionut Leonte <ionut.leonte@gmail.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/b44.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -679,6 +679,7 @@ static int b44_alloc_rx_skb(struct b44 *bp, int src_idx, u32 dest_idx_unmasked)
		dev_kfree_skb_any(skb);
		return -ENOMEM;
		}
		bp->force_copybreak = 1;
		}

		rh = (struct rx_header *) skb->data;
		@@ -800,7 +801,7 @@ static int b44_rx(struct b44 *bp, int budget)
		/* Omit CRC. */
		len -= 4;

		if (len > RX_COPY_THRESHOLD) {
		if (!bp->force_copybreak && len > RX_COPY_THRESHOLD) {
		int skb_size;
		skb_size = b44_alloc_rx_skb(bp, cons, bp->rx_prod);
		if (skb_size < 0)
		@@ -2152,6 +2153,7 @@ static int __devinit b44_init_one(struct ssb_device *sdev,
		bp = netdev_priv(dev);
		bp->sdev = sdev;
		bp->dev = dev;
		bp->force_copybreak = 0;

		bp->msg_enable = netif_msg_init(b44_debug, B44_DEF_MSG_ENABLE);

drivers/net/b44.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -395,7 +395,7 @@ struct b44 {
		u32 rx_pending;
		u32 tx_pending;
		u8 phy_addr;

		u8 force_copybreak;
		struct mii_if_info mii_if;
		};

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