-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.

There is currently an object (`msg`) in multiple structures that
contains a flexible structure (`struct glink_msg`), for example:

struct glink_defer_cmd {
        ...

        struct glink_msg msg;
        u8 data[];
};

So, in order to avoid ending up with a flexible-array member in the
middle of another structure, we use the `__struct_group()` helper
to separate the flexible array from the rest of the members in the
flexible structure:

struct glink_msg {
        __struct_group(glink_msg_hdr, hdr, __packed,

        ... the rest of members

        );
        u8 data[];
} __packed;

With the change described above, we now declare objects of the type of
the tagged struct, in this case `struct glink_msg_hdr`, without
embedding flexible arrays in the middle of other structures:

struct glink_defer_cmd {
        ...

        struct glink_msg_hdr msg;
        u8 data[];
};

Also, use `container_of()` to retrieve a pointer to the flexible structure.

We also use the `DEFINE_RAW_FLEX()` helper for an in-stack definition of
a flexible structure where the size of the flexible-array member is known
at compile-time.

So, with these changes, fix the following warnings:
drivers/rpmsg/qcom_glink_native.c:51:26: warning: structure containing a 
flexible array member is not at the end of another structure 
[-Wflex-array-member-not-at-end]
drivers/rpmsg/qcom_glink_native.c:459:34: warning: structure containing a 
flexible array member is not at the end of another structure 
[-Wflex-array-member-not-at-end]
drivers/rpmsg/qcom_glink_native.c:846:34: warning: structure containing a 
flexible array member is not at the end of another structure 
[-Wflex-array-member-not-at-end]
drivers/rpmsg/qcom_glink_native.c:968:34: warning: structure containing a 
flexible array member is not at the end of another structure 
[-Wflex-array-member-not-at-end]
drivers/rpmsg/qcom_glink_native.c:1380:34: warning: structure containing a 
flexible array member is not at the end of another structure 
[-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
 drivers/rpmsg/qcom_glink_native.c | 38 ++++++++++++++++---------------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/drivers/rpmsg/qcom_glink_native.c 
b/drivers/rpmsg/qcom_glink_native.c
index 82d460ff4777..878e3461bce1 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -30,9 +30,12 @@
 #define RPM_GLINK_CID_MAX      65536
 
 struct glink_msg {
-       __le16 cmd;
-       __le16 param1;
-       __le32 param2;
+       /* New members must be added within the __struct_group() macro below. */
+       __struct_group(glink_msg_hdr, hdr, __packed,
+               __le16 cmd;
+               __le16 param1;
+               __le32 param2;
+       );
        u8 data[];
 } __packed;
 
@@ -48,7 +51,7 @@ struct glink_msg {
 struct glink_defer_cmd {
        struct list_head node;
 
-       struct glink_msg msg;
+       struct glink_msg_hdr msg;
        u8 data[];
 };
 
@@ -455,12 +458,9 @@ static void qcom_glink_intent_req_abort(struct 
glink_channel *channel)
 static int qcom_glink_send_open_req(struct qcom_glink *glink,
                                    struct glink_channel *channel)
 {
-       struct {
-               struct glink_msg msg;
-               u8 name[GLINK_NAME_SIZE];
-       } __packed req;
+       DEFINE_RAW_FLEX(struct glink_msg, req, data, GLINK_NAME_SIZE);
        int name_len = strlen(channel->name) + 1;
-       int req_len = ALIGN(sizeof(req.msg) + name_len, 8);
+       int req_len = ALIGN(sizeof(*req) + name_len, 8);
        int ret;
        unsigned long flags;
 
@@ -476,10 +476,10 @@ static int qcom_glink_send_open_req(struct qcom_glink 
*glink,
 
        channel->lcid = ret;
 
-       req.msg.cmd = cpu_to_le16(GLINK_CMD_OPEN);
-       req.msg.param1 = cpu_to_le16(channel->lcid);
-       req.msg.param2 = cpu_to_le32(name_len);
-       strcpy(req.name, channel->name);
+       req->cmd = cpu_to_le16(GLINK_CMD_OPEN);
+       req->param1 = cpu_to_le16(channel->lcid);
+       req->param2 = cpu_to_le32(name_len);
+       strcpy(req->data, channel->name);
 
        ret = qcom_glink_tx(glink, &req, req_len, NULL, 0, true);
        if (ret)
@@ -826,7 +826,9 @@ static int qcom_glink_rx_defer(struct qcom_glink *glink, 
size_t extra)
 
        INIT_LIST_HEAD(&dcmd->node);
 
-       qcom_glink_rx_peek(glink, &dcmd->msg, 0, sizeof(dcmd->msg) + extra);
+       qcom_glink_rx_peek(glink,
+                          container_of(&dcmd->msg, struct glink_msg, hdr), 0,
+                          sizeof(dcmd->msg) + extra);
 
        spin_lock(&glink->rx_lock);
        list_add_tail(&dcmd->node, &glink->rx_queue);
@@ -843,7 +845,7 @@ static int qcom_glink_rx_data(struct qcom_glink *glink, 
size_t avail)
        struct glink_core_rx_intent *intent;
        struct glink_channel *channel;
        struct {
-               struct glink_msg msg;
+               struct glink_msg_hdr msg;
                __le32 chunk_size;
                __le32 left_size;
        } __packed hdr;
@@ -965,7 +967,7 @@ static void qcom_glink_handle_intent(struct qcom_glink 
*glink,
        };
 
        struct {
-               struct glink_msg msg;
+               struct glink_msg_hdr msg;
                struct intent_pair intents[];
        } __packed * msg;
 
@@ -1377,7 +1379,7 @@ static int __qcom_glink_send(struct glink_channel 
*channel,
        struct glink_core_rx_intent *tmp;
        int iid = 0;
        struct {
-               struct glink_msg msg;
+               struct glink_msg_hdr msg;
                __le32 chunk_size;
                __le32 left_size;
        } __packed req;
@@ -1685,7 +1687,7 @@ static void qcom_glink_work(struct work_struct *work)
                list_del(&dcmd->node);
                spin_unlock_irqrestore(&glink->rx_lock, flags);
 
-               msg = &dcmd->msg;
+               msg = container_of(&dcmd->msg, struct glink_msg, hdr);
                cmd = le16_to_cpu(msg->cmd);
                param1 = le16_to_cpu(msg->param1);
                param2 = le32_to_cpu(msg->param2);
-- 
2.34.1


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