net: stmmac: add GSO MSS checks

Add GSO MSS checks to stmmac_features_check().

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1w7ptT-0000000EatI-3feh@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index c23de66227245cd1028197472d8cc886e11c3854..e6dff31188e6d09a272aee38249d5d06b01df743 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4391,12 +4391,19 @@ static size_t stmmac_tso_header_size(struct sk_buff *skb)
  *
  * While IPv4 is limited to MAC+VLAN+IPv4+ext+TCP+ext = 138 bytes, the IPv6
  * extension headers aren't similarly limited.
+ *
+ * Fall back to software GSO for these skbs. Also check that the MSS is >=
+ * the recommended 64 bytes (documented in ETH_DMACxCR register description),
+ * and that a the header plus MSS is not larger than 16383 (documented in
+ * "Building the Descriptor and the packet for the TSO feature").
  */
 static bool stmmac_tso_valid_packet(struct sk_buff *skb)
 {
        size_t header_len = stmmac_tso_header_size(skb);
+       unsigned int gso_size = skb_shinfo(skb)->gso_size;
 
-       return header_len <= 1023;
+       return header_len <= 1023 && gso_size >= 64 &&
+              header_len + gso_size < 16383;
 }
 
 /**