The compiler has trouble understanding that the code is actually pointing
at the data in the message past the nh struct.

Update the tap_nlattr_add* helpers and the NLMSG_TAIL macro passing a
pointer to msg.

Bugzilla ID: 1511
Fixes: 7c25284e30c2 ("net/tap: add netlink back-end for flow API")
Cc: [email protected]

Signed-off-by: David Marchand <[email protected]>
---
 drivers/net/tap/tap_flow.c    | 117 +++++++++++++---------------------
 drivers/net/tap/tap_netlink.c |  24 +++----
 drivers/net/tap/tap_netlink.h |  10 +--
 drivers/net/tap/tap_tcmsgs.c  |   6 +-
 4 files changed, 65 insertions(+), 92 deletions(-)

diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
index 373b773e2d..9d4ef27a8a 100644
--- a/drivers/net/tap/tap_flow.c
+++ b/drivers/net/tap/tap_flow.c
@@ -430,20 +430,16 @@ tap_flow_create_eth(const struct rte_flow_item *item, 
struct convert_data *info)
                return 0;
        msg = &flow->msg;
        if (!rte_is_zero_ether_addr(&mask->hdr.dst_addr)) {
-               tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_ETH_DST,
-                       RTE_ETHER_ADDR_LEN,
-                          &spec->hdr.dst_addr.addr_bytes);
-               tap_nlattr_add(&msg->nh,
-                          TCA_FLOWER_KEY_ETH_DST_MASK, RTE_ETHER_ADDR_LEN,
-                          &mask->hdr.dst_addr.addr_bytes);
+               tap_nlattr_add(msg, TCA_FLOWER_KEY_ETH_DST, RTE_ETHER_ADDR_LEN,
+                       &spec->hdr.dst_addr.addr_bytes);
+               tap_nlattr_add(msg, TCA_FLOWER_KEY_ETH_DST_MASK, 
RTE_ETHER_ADDR_LEN,
+                       &mask->hdr.dst_addr.addr_bytes);
        }
        if (!rte_is_zero_ether_addr(&mask->hdr.src_addr)) {
-               tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_ETH_SRC,
-                       RTE_ETHER_ADDR_LEN,
+               tap_nlattr_add(msg, TCA_FLOWER_KEY_ETH_SRC, RTE_ETHER_ADDR_LEN,
                        &spec->hdr.src_addr.addr_bytes);
-               tap_nlattr_add(&msg->nh,
-                          TCA_FLOWER_KEY_ETH_SRC_MASK, RTE_ETHER_ADDR_LEN,
-                          &mask->hdr.src_addr.addr_bytes);
+               tap_nlattr_add(msg, TCA_FLOWER_KEY_ETH_SRC_MASK, 
RTE_ETHER_ADDR_LEN,
+                       &mask->hdr.src_addr.addr_bytes);
        }
        return 0;
 }
@@ -498,11 +494,9 @@ tap_flow_create_vlan(const struct rte_flow_item *item, 
struct convert_data *info
                uint8_t vid = VLAN_ID(tci);
 
                if (prio)
-                       tap_nlattr_add8(&msg->nh,
-                                       TCA_FLOWER_KEY_VLAN_PRIO, prio);
+                       tap_nlattr_add8(msg, TCA_FLOWER_KEY_VLAN_PRIO, prio);
                if (vid)
-                       tap_nlattr_add16(&msg->nh,
-                                        TCA_FLOWER_KEY_VLAN_ID, vid);
+                       tap_nlattr_add16(msg, TCA_FLOWER_KEY_VLAN_ID, vid);
        }
        return 0;
 }
@@ -544,20 +538,15 @@ tap_flow_create_ipv4(const struct rte_flow_item *item, 
struct convert_data *info
        if (!spec)
                return 0;
        if (mask->hdr.dst_addr) {
-               tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST,
-                            spec->hdr.dst_addr);
-               tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST_MASK,
-                            mask->hdr.dst_addr);
+               tap_nlattr_add32(msg, TCA_FLOWER_KEY_IPV4_DST, 
spec->hdr.dst_addr);
+               tap_nlattr_add32(msg, TCA_FLOWER_KEY_IPV4_DST_MASK, 
mask->hdr.dst_addr);
        }
        if (mask->hdr.src_addr) {
-               tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC,
-                            spec->hdr.src_addr);
-               tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC_MASK,
-                            mask->hdr.src_addr);
+               tap_nlattr_add32(msg, TCA_FLOWER_KEY_IPV4_SRC, 
spec->hdr.src_addr);
+               tap_nlattr_add32(msg, TCA_FLOWER_KEY_IPV4_SRC_MASK, 
mask->hdr.src_addr);
        }
        if (spec->hdr.next_proto_id)
-               tap_nlattr_add8(&msg->nh, TCA_FLOWER_KEY_IP_PROTO,
-                           spec->hdr.next_proto_id);
+               tap_nlattr_add8(msg, TCA_FLOWER_KEY_IP_PROTO, 
spec->hdr.next_proto_id);
        return 0;
 }
 
@@ -599,20 +588,19 @@ tap_flow_create_ipv6(const struct rte_flow_item *item, 
struct convert_data *info
        if (!spec)
                return 0;
        if (memcmp(&mask->hdr.dst_addr, empty_addr, 16)) {
-               tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST,
-                          sizeof(spec->hdr.dst_addr), &spec->hdr.dst_addr);
-               tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST_MASK,
-                          sizeof(mask->hdr.dst_addr), &mask->hdr.dst_addr);
+               tap_nlattr_add(msg, TCA_FLOWER_KEY_IPV6_DST, 
sizeof(spec->hdr.dst_addr),
+                       &spec->hdr.dst_addr);
+               tap_nlattr_add(msg, TCA_FLOWER_KEY_IPV6_DST_MASK, 
sizeof(mask->hdr.dst_addr),
+                       &mask->hdr.dst_addr);
        }
        if (memcmp(&mask->hdr.src_addr, empty_addr, 16)) {
-               tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC,
-                          sizeof(spec->hdr.src_addr), &spec->hdr.src_addr);
-               tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC_MASK,
-                          sizeof(mask->hdr.src_addr), &mask->hdr.src_addr);
+               tap_nlattr_add(msg, TCA_FLOWER_KEY_IPV6_SRC, 
sizeof(spec->hdr.src_addr),
+                       &spec->hdr.src_addr);
+               tap_nlattr_add(msg, TCA_FLOWER_KEY_IPV6_SRC_MASK, 
sizeof(mask->hdr.src_addr),
+                       &mask->hdr.src_addr);
        }
        if (spec->hdr.proto)
-               tap_nlattr_add8(&msg->nh,
-                               TCA_FLOWER_KEY_IP_PROTO, spec->hdr.proto);
+               tap_nlattr_add8(msg, TCA_FLOWER_KEY_IP_PROTO, spec->hdr.proto);
        return 0;
 }
 
@@ -649,15 +637,13 @@ tap_flow_create_udp(const struct rte_flow_item *item, 
struct convert_data *info)
        if (!flow)
                return 0;
        msg = &flow->msg;
-       tap_nlattr_add8(&msg->nh, TCA_FLOWER_KEY_IP_PROTO, IPPROTO_UDP);
+       tap_nlattr_add8(msg, TCA_FLOWER_KEY_IP_PROTO, IPPROTO_UDP);
        if (!spec)
                return 0;
        if (mask->hdr.dst_port)
-               tap_nlattr_add16(&msg->nh, TCA_FLOWER_KEY_UDP_DST,
-                            spec->hdr.dst_port);
+               tap_nlattr_add16(msg, TCA_FLOWER_KEY_UDP_DST, 
spec->hdr.dst_port);
        if (mask->hdr.src_port)
-               tap_nlattr_add16(&msg->nh, TCA_FLOWER_KEY_UDP_SRC,
-                            spec->hdr.src_port);
+               tap_nlattr_add16(msg, TCA_FLOWER_KEY_UDP_SRC, 
spec->hdr.src_port);
        return 0;
 }
 
@@ -694,15 +680,13 @@ tap_flow_create_tcp(const struct rte_flow_item *item, 
struct convert_data *info)
        if (!flow)
                return 0;
        msg = &flow->msg;
-       tap_nlattr_add8(&msg->nh, TCA_FLOWER_KEY_IP_PROTO, IPPROTO_TCP);
+       tap_nlattr_add8(msg, TCA_FLOWER_KEY_IP_PROTO, IPPROTO_TCP);
        if (!spec)
                return 0;
        if (mask->hdr.dst_port)
-               tap_nlattr_add16(&msg->nh, TCA_FLOWER_KEY_TCP_DST,
-                            spec->hdr.dst_port);
+               tap_nlattr_add16(msg, TCA_FLOWER_KEY_TCP_DST, 
spec->hdr.dst_port);
        if (mask->hdr.src_port)
-               tap_nlattr_add16(&msg->nh, TCA_FLOWER_KEY_TCP_SRC,
-                            spec->hdr.src_port);
+               tap_nlattr_add16(msg, TCA_FLOWER_KEY_TCP_SRC, 
spec->hdr.src_port);
        return 0;
 }
 
@@ -810,37 +794,30 @@ add_action(struct rte_flow *flow, size_t *act_index, 
struct action_data *adata)
        if (tap_nlattr_nested_start(msg, (*act_index)++) < 0)
                return -1;
 
-       tap_nlattr_add(&msg->nh, TCA_ACT_KIND,
-                               strlen(adata->id) + 1, adata->id);
+       tap_nlattr_add(msg, TCA_ACT_KIND, strlen(adata->id) + 1, adata->id);
        if (tap_nlattr_nested_start(msg, TCA_ACT_OPTIONS) < 0)
                return -1;
        if (strcmp("gact", adata->id) == 0) {
-               tap_nlattr_add(&msg->nh, TCA_GACT_PARMS, sizeof(adata->gact),
-                          &adata->gact);
+               tap_nlattr_add(msg, TCA_GACT_PARMS, sizeof(adata->gact), 
&adata->gact);
        } else if (strcmp("mirred", adata->id) == 0) {
                if (adata->mirred.eaction == TCA_EGRESS_MIRROR)
                        adata->mirred.action = TC_ACT_PIPE;
                else /* REDIRECT */
                        adata->mirred.action = TC_ACT_STOLEN;
-               tap_nlattr_add(&msg->nh, TCA_MIRRED_PARMS,
-                          sizeof(adata->mirred),
-                          &adata->mirred);
+               tap_nlattr_add(msg, TCA_MIRRED_PARMS, sizeof(adata->mirred), 
&adata->mirred);
        } else if (strcmp("skbedit", adata->id) == 0) {
-               tap_nlattr_add(&msg->nh, TCA_SKBEDIT_PARMS,
-                          sizeof(adata->skbedit.skbedit), 
&adata->skbedit.skbedit);
+               tap_nlattr_add(msg, TCA_SKBEDIT_PARMS, 
sizeof(adata->skbedit.skbedit),
+                       &adata->skbedit.skbedit);
                if (adata->skbedit.mark)
-                       tap_nlattr_add32(&msg->nh, TCA_SKBEDIT_MARK, 
adata->skbedit.mark);
+                       tap_nlattr_add32(msg, TCA_SKBEDIT_MARK, 
adata->skbedit.mark);
                else
-                       tap_nlattr_add16(&msg->nh, TCA_SKBEDIT_QUEUE_MAPPING, 
adata->skbedit.queue);
+                       tap_nlattr_add16(msg, TCA_SKBEDIT_QUEUE_MAPPING, 
adata->skbedit.queue);
        } else if (strcmp("bpf", adata->id) == 0) {
 #ifdef HAVE_BPF_RSS
-               tap_nlattr_add32(&msg->nh, TCA_ACT_BPF_FD, adata->bpf.bpf_fd);
-               tap_nlattr_add(&msg->nh, TCA_ACT_BPF_NAME,
-                          strlen(adata->bpf.annotation) + 1,
-                          adata->bpf.annotation);
-               tap_nlattr_add(&msg->nh, TCA_ACT_BPF_PARMS,
-                          sizeof(adata->bpf.bpf),
-                          &adata->bpf.bpf);
+               tap_nlattr_add32(msg, TCA_ACT_BPF_FD, adata->bpf.bpf_fd);
+               tap_nlattr_add(msg, TCA_ACT_BPF_NAME, 
strlen(adata->bpf.annotation) + 1,
+                       adata->bpf.annotation);
+               tap_nlattr_add(msg, TCA_ACT_BPF_PARMS, sizeof(adata->bpf.bpf), 
&adata->bpf.bpf);
 #else
                TAP_LOG(ERR, "Internal error: bpf requested but not supported");
                return -1;
@@ -975,7 +952,7 @@ priv_flow_process(struct pmd_internals *pmd,
                                TC_H_MAKE(MULTIQ_MAJOR_HANDLE, 0);
                }
                /* use flower filter type */
-               tap_nlattr_add(&flow->msg.nh, TCA_KIND, sizeof("flower"), 
"flower");
+               tap_nlattr_add(&flow->msg, TCA_KIND, sizeof("flower"), 
"flower");
                if (tap_nlattr_nested_start(&flow->msg, TCA_OPTIONS) < 0) {
                        rte_flow_error_set(error, ENOMEM, 
RTE_FLOW_ERROR_TYPE_ACTION,
                                           actions, "could not allocated 
netlink msg");
@@ -1015,15 +992,11 @@ priv_flow_process(struct pmd_internals *pmd,
        }
        if (flow) {
                if (data.vlan) {
-                       tap_nlattr_add16(&flow->msg.nh, TCA_FLOWER_KEY_ETH_TYPE,
-                                    htons(ETH_P_8021Q));
-                       tap_nlattr_add16(&flow->msg.nh,
-                                    TCA_FLOWER_KEY_VLAN_ETH_TYPE,
-                                    data.eth_type ?
-                                    data.eth_type : htons(ETH_P_ALL));
+                       tap_nlattr_add16(&flow->msg, TCA_FLOWER_KEY_ETH_TYPE, 
htons(ETH_P_8021Q));
+                       tap_nlattr_add16(&flow->msg, 
TCA_FLOWER_KEY_VLAN_ETH_TYPE,
+                               data.eth_type ?  data.eth_type : 
htons(ETH_P_ALL));
                } else if (data.eth_type) {
-                       tap_nlattr_add16(&flow->msg.nh, TCA_FLOWER_KEY_ETH_TYPE,
-                                    data.eth_type);
+                       tap_nlattr_add16(&flow->msg, TCA_FLOWER_KEY_ETH_TYPE, 
data.eth_type);
                }
        }
        if (mirred && flow) {
diff --git a/drivers/net/tap/tap_netlink.c b/drivers/net/tap/tap_netlink.c
index 8a57c9242c..5ff60f41d4 100644
--- a/drivers/net/tap/tap_netlink.c
+++ b/drivers/net/tap/tap_netlink.c
@@ -293,18 +293,18 @@ tap_nl_recv(int nlsk_fd, int (*cb)(struct nlmsghdr *, 
void *arg), void *arg)
  *   The data to append.
  */
 void
-tap_nlattr_add(struct nlmsghdr *nh, unsigned short type,
+tap_nlattr_add(struct tap_nlmsg *msg, unsigned short type,
           unsigned int data_len, const void *data)
 {
        /* see man 3 rtnetlink */
        struct rtattr *rta;
 
-       rta = (struct rtattr *)NLMSG_TAIL(nh);
+       rta = (struct rtattr *)NLMSG_TAIL(msg);
        rta->rta_len = RTA_LENGTH(data_len);
        rta->rta_type = type;
        if (data_len > 0)
                memcpy(RTA_DATA(rta), data, data_len);
-       nh->nlmsg_len = NLMSG_ALIGN(nh->nlmsg_len) + RTA_ALIGN(rta->rta_len);
+       msg->nh.nlmsg_len = NLMSG_ALIGN(msg->nh.nlmsg_len) + 
RTA_ALIGN(rta->rta_len);
 }
 
 /**
@@ -318,9 +318,9 @@ tap_nlattr_add(struct nlmsghdr *nh, unsigned short type,
  *   The data to append.
  */
 void
-tap_nlattr_add8(struct nlmsghdr *nh, unsigned short type, uint8_t data)
+tap_nlattr_add8(struct tap_nlmsg *msg, unsigned short type, uint8_t data)
 {
-       tap_nlattr_add(nh, type, sizeof(uint8_t), &data);
+       tap_nlattr_add(msg, type, sizeof(uint8_t), &data);
 }
 
 /**
@@ -334,9 +334,9 @@ tap_nlattr_add8(struct nlmsghdr *nh, unsigned short type, 
uint8_t data)
  *   The data to append.
  */
 void
-tap_nlattr_add16(struct nlmsghdr *nh, unsigned short type, uint16_t data)
+tap_nlattr_add16(struct tap_nlmsg *msg, unsigned short type, uint16_t data)
 {
-       tap_nlattr_add(nh, type, sizeof(uint16_t), &data);
+       tap_nlattr_add(msg, type, sizeof(uint16_t), &data);
 }
 
 /**
@@ -350,9 +350,9 @@ tap_nlattr_add16(struct nlmsghdr *nh, unsigned short type, 
uint16_t data)
  *   The data to append.
  */
 void
-tap_nlattr_add32(struct nlmsghdr *nh, unsigned short type, uint32_t data)
+tap_nlattr_add32(struct tap_nlmsg *msg, unsigned short type, uint32_t data)
 {
-       tap_nlattr_add(nh, type, sizeof(uint32_t), &data);
+       tap_nlattr_add(msg, type, sizeof(uint32_t), &data);
 }
 
 /**
@@ -379,9 +379,9 @@ tap_nlattr_nested_start(struct tap_nlmsg *msg, uint16_t 
type)
                return -1;
        }
 
-       tail->tail = (struct rtattr *)NLMSG_TAIL(&msg->nh);
+       tail->tail = (struct rtattr *)NLMSG_TAIL(msg);
 
-       tap_nlattr_add(&msg->nh, type, 0, NULL);
+       tap_nlattr_add(msg, type, 0, NULL);
 
        tail->prev = msg->nested_tails;
 
@@ -404,7 +404,7 @@ tap_nlattr_nested_finish(struct tap_nlmsg *msg)
 {
        struct nested_tail *tail = msg->nested_tails;
 
-       tail->tail->rta_len = (char *)NLMSG_TAIL(&msg->nh) - (char *)tail->tail;
+       tail->tail->rta_len = (char *)NLMSG_TAIL(msg) - (char *)tail->tail;
 
        if (tail->prev)
                msg->nested_tails = tail->prev;
diff --git a/drivers/net/tap/tap_netlink.h b/drivers/net/tap/tap_netlink.h
index 466c47a6d7..5eff6edbb1 100644
--- a/drivers/net/tap/tap_netlink.h
+++ b/drivers/net/tap/tap_netlink.h
@@ -23,7 +23,7 @@ struct tap_nlmsg {
        struct nested_tail *nested_tails;
 };
 
-#define NLMSG_TAIL(nlh) (void *)((char *)(nlh) + NLMSG_ALIGN((nlh)->nlmsg_len))
+#define NLMSG_TAIL(msg) (void *)((char *)(msg) + 
NLMSG_ALIGN((msg)->nh.nlmsg_len))
 
 int tap_nl_init(uint32_t nl_groups);
 int tap_nl_final(int nlsk_fd);
@@ -31,11 +31,11 @@ int tap_nl_send(int nlsk_fd, struct nlmsghdr *nh);
 int tap_nl_recv(int nlsk_fd, int (*callback)(struct nlmsghdr *, void *),
                void *arg);
 int tap_nl_recv_ack(int nlsk_fd);
-void tap_nlattr_add(struct nlmsghdr *nh, unsigned short type,
+void tap_nlattr_add(struct tap_nlmsg *msg, unsigned short type,
                    unsigned int data_len, const void *data);
-void tap_nlattr_add8(struct nlmsghdr *nh, unsigned short type, uint8_t data);
-void tap_nlattr_add16(struct nlmsghdr *nh, unsigned short type, uint16_t data);
-void tap_nlattr_add32(struct nlmsghdr *nh, unsigned short type, uint32_t data);
+void tap_nlattr_add8(struct tap_nlmsg *msg, unsigned short type, uint8_t data);
+void tap_nlattr_add16(struct tap_nlmsg *msg, unsigned short type, uint16_t 
data);
+void tap_nlattr_add32(struct tap_nlmsg *msg, unsigned short type, uint32_t 
data);
 int tap_nlattr_nested_start(struct tap_nlmsg *msg, uint16_t type);
 void tap_nlattr_nested_finish(struct tap_nlmsg *msg);
 
diff --git a/drivers/net/tap/tap_tcmsgs.c b/drivers/net/tap/tap_tcmsgs.c
index caca9445c8..c32f0ff815 100644
--- a/drivers/net/tap/tap_tcmsgs.c
+++ b/drivers/net/tap/tap_tcmsgs.c
@@ -123,8 +123,8 @@ qdisc_add_multiq(int nlsk_fd, unsigned int ifindex)
                    NLM_F_REQUEST | NLM_F_ACK | NLM_F_EXCL | NLM_F_CREATE);
        msg.t.tcm_handle = TC_H_MAKE(MULTIQ_MAJOR_HANDLE, 0);
        msg.t.tcm_parent = TC_H_ROOT;
-       tap_nlattr_add(&msg.nh, TCA_KIND, sizeof("multiq"), "multiq");
-       tap_nlattr_add(&msg.nh, TCA_OPTIONS, sizeof(opt), &opt);
+       tap_nlattr_add(&msg, TCA_KIND, sizeof("multiq"), "multiq");
+       tap_nlattr_add(&msg, TCA_OPTIONS, sizeof(opt), &opt);
        if (tap_nl_send(nlsk_fd, &msg.nh) < 0)
                return -1;
        if (tap_nl_recv_ack(nlsk_fd) < 0)
@@ -152,7 +152,7 @@ qdisc_add_ingress(int nlsk_fd, unsigned int ifindex)
                    NLM_F_REQUEST | NLM_F_ACK | NLM_F_EXCL | NLM_F_CREATE);
        msg.t.tcm_handle = TC_H_MAKE(TC_H_INGRESS, 0);
        msg.t.tcm_parent = TC_H_INGRESS;
-       tap_nlattr_add(&msg.nh, TCA_KIND, sizeof("ingress"), "ingress");
+       tap_nlattr_add(&msg, TCA_KIND, sizeof("ingress"), "ingress");
        if (tap_nl_send(nlsk_fd, &msg.nh) < 0)
                return -1;
        if (tap_nl_recv_ack(nlsk_fd) < 0)
-- 
2.51.0

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