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* [PATCH v3] net: mana: Fix return type of mana_start_xmit()
@ 2022-11-09  0:26 Nathan Chancellor
  2022-11-10 11:40 ` patchwork-bot+netdevbpf
  0 siblings, 1 reply; 2+ messages in thread
From: Nathan Chancellor @ 2022-11-09  0:26 UTC (permalink / raw)
  To: K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger, Wei Liu,
	Dexuan Cui, David S. Miller, Eric Dumazet, Jakub Kicinski,
	Paolo Abeni
  Cc: linux-hyperv, netdev, Nick Desaulniers, Tom Rix, Kees Cook,
	Sami Tolvanen, llvm, linux-kernel, patches, Nathan Huckleberry,
	Dan Carpenter, Nathan Chancellor

From: Nathan Huckleberry <>

The ndo_start_xmit field in net_device_ops is expected to be of type
netdev_tx_t (*ndo_start_xmit)(struct sk_buff *skb, struct net_device *dev).

The mismatched return type breaks forward edge kCFI since the underlying
function definition does not match the function hook definition. A new
warning in clang will catch this at compile time:

  drivers/net/ethernet/microsoft/mana/mana_en.c:382:21: error: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an expression of type 'int (struct sk_buff *, struct net_device *)' [-Werror,-Wincompatible-function-pointer-types-strict]
          .ndo_start_xmit         = mana_start_xmit,
  1 error generated.

The return type of mana_start_xmit should be changed from int to

Reported-by: Dan Carpenter <>
Signed-off-by: Nathan Huckleberry <>
Reviewed-by: Dexuan Cui <>
[nathan: Rebase on net-next and resolve conflicts
         Add note about new clang warning]
Signed-off-by: Nathan Chancellor <>

  - Take over for Nathan, as he is busy with other matters.
  - Rebase on net-next and resolve conflicts.
  - Add a note about new clang warning that will catch this issue at
    compile time.


 drivers/net/ethernet/microsoft/mana/mana.h    | 2 +-
 drivers/net/ethernet/microsoft/mana/mana_en.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/mana.h b/drivers/net/ethernet/microsoft/mana/mana.h
index d58be64374c8..ffcd27cde17b 100644
--- a/drivers/net/ethernet/microsoft/mana/mana.h
+++ b/drivers/net/ethernet/microsoft/mana/mana.h
@@ -388,7 +388,7 @@ struct mana_port_context {
 	struct mana_ethtool_stats eth_stats;
-int mana_start_xmit(struct sk_buff *skb, struct net_device *ndev);
+netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev);
 int mana_config_rss(struct mana_port_context *ac, enum TRI_STATE rx,
 		    bool update_hash, bool update_tab);
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index 318dbbb48279..91a8d3577c14 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -128,7 +128,7 @@ static int mana_map_skb(struct sk_buff *skb, struct mana_port_context *apc,
 	return -ENOMEM;
-int mana_start_xmit(struct sk_buff *skb, struct net_device *ndev)
+netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	enum mana_tx_pkt_format pkt_fmt = MANA_SHORT_PKT_FMT;
 	struct mana_port_context *apc = netdev_priv(ndev);

base-commit: 8e18be7610aebea50e9327c11afcd5eeaaa06644

^ permalink raw reply related	[flat|nested] 2+ messages in thread

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2022-11-09  0:26 [PATCH v3] net: mana: Fix return type of mana_start_xmit() Nathan Chancellor
2022-11-10 11:40 ` patchwork-bot+netdevbpf

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