-----Original Message-----
From: Daniel Axtens [mailto:dja@axtens.net]
Sent: Wednesday, January 31, 2018 8:46 AM
To: netdev@vger.kernel.org
Cc: Daniel Axtens <redacted>; Eric Dumazet <redacted>;
Chopra, Manish [off-list ref]; Jason Wang
[off-list ref]; Pravin Shelar [off-list ref]; Marcelo Ricardo
Leitner [off-list ref]
Subject: [PATCH v4 2/2] bnx2x: disable GSO where gso_size is too big for
hardware

If a bnx2x card is passed a GSO packet with a gso_size larger than
~9700 bytes, it will cause a firmware error that will bring the card
down:

bnx2x: [bnx2x_attn_int_deasserted3:4323(enP24p1s0f0)]MC assert!
bnx2x: [bnx2x_mc_assert:720(enP24p1s0f0)]XSTORM_ASSERT_LIST_INDEX 0x2
bnx2x: [bnx2x_mc_assert:736(enP24p1s0f0)]XSTORM_ASSERT_INDEX 0x0 =
0x00000000 0x25e43e47 0x00463e01 0x00010052
bnx2x: [bnx2x_mc_assert:750(enP24p1s0f0)]Chip Revision: everest3, FW
Version: 7_13_1 ... (dump of values continues) ...

Detect when the mac length of a GSO packet is greater than the maximum
packet size (9700 bytes) and disable GSO.

Signed-off-by: Daniel Axtens <redacted>

---

v4: Only call the slow check if the gso_size is large.
    Eric - I think this is what you had in mind?
    Manish - do you think this is an acceptable performance trade-off?
             GSO will work for any packet size, and only jumbo frames will
	     have to do the slower test.

Again, only build-tested.
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c | 18
++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
index 7b08323e3f3d..74fc9af4aadb 100644

--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

@@ -12934,6 +12934,24 @@ static netdev_features_t

bnx2x_features_check(struct sk_buff *skb,
 					      struct net_device *dev,
 					      netdev_features_t features)
 {
+	/*
+	 * A skb with gso_size + header length > 9700 will cause a
+	 * firmware panic. Drop GSO support.
+	 *
+	 * Eventually the upper layer should not pass these packets down.
+	 *
+	 * For speed, if the gso_size is <= 9000, assume there will
+	 * not be 700 bytes of headers and pass it through. Only do a
+	 * full (slow) validation if the gso_size is > 9000.
+	 *
+	 * (Due to the way SKB_BY_FRAGS works this will also do a full
+	 * validation in that case.)
+	 */
+	if (unlikely(skb_is_gso(skb) &&
+		     (skb_shinfo(skb)->gso_size > 9000) &&
+		     !skb_gso_validate_mac_len(skb, 9700)))
+		features &= ~NETIF_F_GSO_MASK;