netdev - Re: e100 + VLANs?

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Message-ID: <CAL4WiiphpyizVaNkvOdJp1+UK53TkGw9RXnC-vzH7fTNpBAAEA@mail.gmail.com>
Date:	Tue, 11 Oct 2011 13:25:22 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Michael Tokarev <mjt@....msk.ru>
Cc:	David Lamparter <equinox@...c24.net>, jeffrey.t.kirsher@...el.com,
	netdev <netdev@...r.kernel.org>
Subject: Re: e100 + VLANs?

> So, is that a hardware limitation?

Its a driver bug

This comes from fact that sizeof(struct rfd) = 16

and VLAN_ETH_FRAME_LEN is 1518

driver mixes VLAN_ETH_FRAME_LEN and 1500+4+sizeof(struct rfd)   (1520, not 1518)

It therefore misses 2 bytes for large frames (VLAN tagged)

Fix is to remove VLAN_ETH_FRAME_LEN references for good...

diff --git a/drivers/net/e100.c b/drivers/net/e100.c
index c1352c6..3287d31 100644
--- a/drivers/net/e100.c
+++ b/drivers/net/e100.c
@@ -435,6 +435,7 @@ struct rfd {
        __le16 actual_size;
        __le16 size;
 };
+#define RFD_BUF_LEN (sizeof(struct rfd) + ETH_DATA_LEN + VLAN_HLEN)

 struct rx {
        struct rx *next, *prev;
@@ -1075,7 +1076,7 @@ static void e100_get_defaults(struct nic *nic)
        /* Template for a freshly allocated RFD */
        nic->blank_rfd.command = 0;
        nic->blank_rfd.rbd = cpu_to_le32(0xFFFFFFFF);
-       nic->blank_rfd.size = cpu_to_le16(VLAN_ETH_FRAME_LEN);
+       nic->blank_rfd.size = cpu_to_le16(RFD_BUF_LEN);

        /* MII setup */
        nic->mii.phy_id_mask = 0x1F;
@@ -1881,7 +1882,6 @@ static inline void e100_start_receiver(struct
nic *nic, struct rx *rx)
        }
 }

-#define RFD_BUF_LEN (sizeof(struct rfd) + VLAN_ETH_FRAME_LEN)
 static int e100_rx_alloc_skb(struct nic *nic, struct rx *rx)
 {
        if (!(rx->skb = netdev_alloc_skb_ip_align(nic->netdev, RFD_BUF_LEN)))
@@ -2058,7 +2058,7 @@ static void e100_rx_clean(struct nic *nic,
unsigned int *work_done,
                pci_dma_sync_single_for_device(nic->pdev,
                        old_before_last_rx->dma_addr, sizeof(struct rfd),
                        PCI_DMA_BIDIRECTIONAL);
-               old_before_last_rfd->size = cpu_to_le16(VLAN_ETH_FRAME_LEN);
+               old_before_last_rfd->size = cpu_to_le16(RFD_BUF_LEN);
                pci_dma_sync_single_for_device(nic->pdev,
                        old_before_last_rx->dma_addr, sizeof(struct rfd),
                        PCI_DMA_BIDIRECTIONAL);

Download attachment "patch" of type "application/octet-stream" (1434 bytes)