Bluetooth: hci.h: Avoid a couple -Wflex-array-member-not-at-end warnings

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

struct hci_std_codecs and struct hci_std_codecs_v2 are flexible structures, this is structures that contain a flexible-array member (__u8 codec[]; and struct hci_std_codec_v2 codec[];, correspondingly.)

Since struct hci_rp_read_local_supported_codecs and struct hci_rp_read_local_supported_codecs_v2 are defined by hardware, we create the new struct hci_std_codecs_hdr and struct hci_std_codecs_v2_hdr types, and use them to replace the object types causing trouble in struct hci_rp_read_local_supported_codecs and struct hci_rp_read_local_supported_codecs_v2, namely struct hci_std_codecs std_codecs; and struct hci_std_codecs_v2_hdr std_codecs;.

Also, once -fms-extensions is enabled, we can use transparent struct members in both struct hci_std_codecs and struct hci_std_codecs_v2_hdr.

Notice that the newly created types does not contain the flex-array member codec, which is the object causing the -Wfamnae warnings.

After these changes, the size of struct hci_rp_read_local_supported_codecs and struct hci_rp_read_local_supported_codecs_v2, along with their member's offsets remain the same, hence the memory layouts don't change:

Before changes:
struct hci_rp_read_local_supported_codecs {

        __u8                       status;               /*     0     1 */
        struct hci_std_codecs      std_codecs;           /*     1     1 */
        struct hci_vnd_codecs      vnd_codecs;           /*     2     1 */

        /* size: 3, cachelines: 1, members: 3 */
        /* last cacheline: 3 bytes */
} __attribute__((__packed__));

struct hci_rp_read_local_supported_codecs_v2 {

        __u8                       status;               /*     0     1 */
        struct hci_std_codecs_v2   std_codecs;           /*     1     1 */
        struct hci_vnd_codecs_v2   vendor_codecs;        /*     2     1 */

        /* size: 3, cachelines: 1, members: 3 */
        /* last cacheline: 3 bytes */
} __attribute__((__packed__));

After changes:
struct hci_rp_read_local_supported_codecs {

	__u8                       status;               /*     0     1 */
	struct hci_std_codecs_hdr  std_codecs;           /*     1     1 */
	struct hci_vnd_codecs      vnd_codecs;           /*     2     1 */

	/* size: 3, cachelines: 1, members: 3 */
	/* last cacheline: 3 bytes */
} __attribute__((__packed__));

struct hci_rp_read_local_supported_codecs_v2 {

	__u8                       status;               /*     0     1 */
	struct hci_std_codecs_v2_hdr std_codecs;         /*     1     1 */
	struct hci_vnd_codecs_v2   vendor_codecs;        /*     2     1 */

	/* size: 3, cachelines: 1, members: 3 */
	/* last cacheline: 3 bytes */
} __attribute__((__packed__));

With these changes fix the following warnings:

include/net/bluetooth/hci.h:1490:31: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/net/bluetooth/hci.h:1525:34: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

---
 include/net/bluetooth/hci.h | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

index 89ad9470fa71..572b1c620c5d 100644
@@ -1468,8 +1468,12 @@ struct hci_rp_read_data_block_size {
 } __packed;
 
 #define HCI_OP_READ_LOCAL_CODECS	0x100b
-struct hci_std_codecs {
+struct hci_std_codecs_hdr {
 	__u8	num;
+} __packed;
+
+struct hci_std_codecs {
+	struct hci_std_codecs_hdr;
 	__u8	codec[];
 } __packed;
 

@@ -1487,7 +1491,7 @@ struct hci_vnd_codecs {
 
 struct hci_rp_read_local_supported_codecs {
 	__u8	status;
-	struct hci_std_codecs std_codecs;
+	struct hci_std_codecs_hdr std_codecs;
 	struct hci_vnd_codecs vnd_codecs;
 } __packed;
 

@@ -1504,8 +1508,12 @@ struct hci_std_codec_v2 {
 	__u8	transport;
 } __packed;
 
-struct hci_std_codecs_v2 {
+struct hci_std_codecs_v2_hdr {
 	__u8	num;
+} __packed;
+
+struct hci_std_codecs_v2 {
+	struct hci_std_codecs_v2_hdr;
 	struct hci_std_codec_v2 codec[];
 } __packed;
 

@@ -1522,7 +1530,7 @@ struct hci_vnd_codecs_v2 {
 
 struct hci_rp_read_local_supported_codecs_v2 {
 	__u8	status;
-	struct hci_std_codecs_v2 std_codecs;
+	struct hci_std_codecs_v2_hdr std_codecs;
 	struct hci_vnd_codecs_v2 vendor_codecs;
 } __packed;
 

2.43.0

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Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list. This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=1078355

---Test result---

Test Summary:

CheckPatch                    PENDING   0.45 seconds
GitLint                       PENDING   0.30 seconds
SubjectPrefix                 PASS      0.10 seconds
BuildKernel                   PASS      26.23 seconds
CheckAllWarning               PASS      28.84 seconds
CheckSparse                   PASS      27.69 seconds
BuildKernel32                 PASS      25.71 seconds
TestRunnerSetup               PASS      576.20 seconds
TestRunner_l2cap-tester       PASS      28.40 seconds
TestRunner_iso-tester         PASS      40.63 seconds
TestRunner_bnep-tester        PASS      6.48 seconds
TestRunner_mgmt-tester        FAIL      115.67 seconds
TestRunner_rfcomm-tester      PASS      9.52 seconds
TestRunner_sco-tester         FAIL      14.64 seconds
TestRunner_ioctl-tester       PASS      10.58 seconds
TestRunner_mesh-tester        FAIL      12.52 seconds
TestRunner_smp-tester         PASS      8.64 seconds
TestRunner_userchan-tester    PASS      6.82 seconds
IncrementalBuild              PENDING   0.50 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner Output:
Total: 494, Passed: 489 (99.0%), Failed: 1, Not Run: 4

Failed Test Cases
Read Exp Feature - Success Failed 0.112 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected

BUG: sleeping function called from invalid context at net/core/sock.c:3782

Total: 30, Passed: 30 (100.0%), Failed: 0, Not Run: 0
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner Output:
Total: 10, Passed: 8 (80.0%), Failed: 2, Not Run: 0

Failed Test Cases

Mesh - Send cancel - 1                               Timed out    2.660 seconds
Mesh - Send cancel - 2                               Timed out    1.995 seconds

##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series Output:

---
Regards,
Linux Bluetooth