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Subject[PATCH AUTOSEL 4.14 016/186] RDMA/netlink: Do not always generate an ACK for some netlink operations
From: Håkon Bugge <>

[ Upstream commit a242c36951ecd24bc16086940dbe6b522205c461 ]

In rdma_nl_rcv_skb(), the local variable err is assigned the return value
of the supplied callback function, which could be one of
ib_nl_handle_resolve_resp(), ib_nl_handle_set_timeout(), or
ib_nl_handle_ip_res_resp(). These three functions all return skb->len on

rdma_nl_rcv_skb() is merely a copy of netlink_rcv_skb(). The callback
functions used by the latter have the convention: "Returns 0 on success or
a negative error code".

In particular, the statement (equal for both functions):

if (nlh->nlmsg_flags & NLM_F_ACK || err)

implies that rdma_nl_rcv_skb() always will ack a message, independent of
the NLM_F_ACK being set in nlmsg_flags or not.

The fix could be to change the above statement, but it is better to keep
the two *_rcv_skb() functions equal in this respect and instead change the
three callback functions in the rdma subsystem to the correct convention.

Fixes: 2ca546b92a02 ("IB/sa: Route SA pathrecord query through netlink")
Fixes: ae43f8286730 ("IB/core: Add IP to GID netlink offload")
Suggested-by: Mark Haywood <>
Signed-off-by: Håkon Bugge <>
Tested-by: Mark Haywood <>
Reviewed-by: Leon Romanovsky <>
Reviewed-by: Jason Gunthorpe <>
Signed-off-by: Jason Gunthorpe <>
Signed-off-by: Sasha Levin <>
drivers/infiniband/core/addr.c | 2 +-
drivers/infiniband/core/sa_query.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index aadaa9e84eeea..c2bbe0df0931c 100644
--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -140,7 +140,7 @@ int ib_nl_handle_ip_res_resp(struct sk_buff *skb,
if (ib_nl_is_good_ip_resp(nlh))

- return skb->len;
+ return 0;

static int ib_nl_ip_send_msg(struct rdma_dev_addr *dev_addr,
diff --git a/drivers/infiniband/core/sa_query.c b/drivers/infiniband/core/sa_query.c
index 50068b0a91fa4..83dad5401c932 100644
--- a/drivers/infiniband/core/sa_query.c
+++ b/drivers/infiniband/core/sa_query.c
@@ -1078,7 +1078,7 @@ int ib_nl_handle_set_timeout(struct sk_buff *skb,

- return skb->len;
+ return 0;

static inline int ib_nl_is_good_resolve_resp(const struct nlmsghdr *nlh)
@@ -1149,7 +1149,7 @@ int ib_nl_handle_resolve_resp(struct sk_buff *skb,

- return skb->len;
+ return 0;

static void free_sm_ah(struct kref *kref)
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