net/smc: Use static_assert() to check struct sizes

Commit 9748dbc9f265 ("net/smc: Avoid -Wflex-array-member-not-at-end warnings") introduced tagged struct smc_clc_v2_extension_fixed and struct smc_clc_smcd_v2_extension_fixed. We want to ensure that when new members need to be added to the flexible structures, they are always included within these tagged structs.

So, we use static_assert() to ensure that the memory layout for both the flexible structure and the tagged struct is the same after any changes.

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
  net/smc/smc_clc.h | 4 ++++
  1 file changed, 4 insertions(+)

net/smc/smc_clc.h +4 -0

index 467effb50cd6..5625fda2960b 100644
@@ -145,6 +145,8 @@ struct smc_clc_v2_extension {
  	);
  	u8 user_eids[][SMC_MAX_EID_LEN];
  };
+static_assert(offsetof(struct smc_clc_v2_extension, user_eids) == sizeof(struct smc_clc_v2_extension_fixed),
+	      "struct member likely outside of struct_group_tagged()");
 
  struct smc_clc_msg_proposal_prefix {	/* prefix part of clc proposal message*/
  	__be32 outgoing_subnet;	/* subnet mask */

@@ -169,6 +171,8 @@ struct smc_clc_smcd_v2_extension {
  	);
  	struct smc_clc_smcd_gid_chid gidchid[];
  };
+static_assert(offsetof(struct smc_clc_smcd_v2_extension, gidchid) == sizeof(struct smc_clc_smcd_v2_extension_fixed),
+	      "struct member likely outside of struct_group_tagged()");
 
  struct smc_clc_msg_proposal {	/* clc proposal message sent by Linux */
  	struct smc_clc_msg_hdr hdr;

Commit 9748dbc9f265 ("net/smc: Avoid -Wflex-array-member-not-at-end warnings") introduced tagged struct smc_clc_v2_extension_fixed and struct smc_clc_smcd_v2_extension_fixed. We want to ensure that when new members need to be added to the flexible structures, they are always included within these tagged structs.

So, we use static_assert() to ensure that the memory layout for both the flexible structure and the tagged struct is the same after any changes.

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
  net/smc/smc_clc.h | 4 ++++
  1 file changed, 4 insertions(+)

net/smc/smc_clc.h +4 -0

index 467effb50cd6..5625fda2960b 100644
@@ -145,6 +145,8 @@ struct smc_clc_v2_extension {
  	);
  	u8 user_eids[][SMC_MAX_EID_LEN];
  };
+static_assert(offsetof(struct smc_clc_v2_extension, user_eids) == sizeof(struct smc_clc_v2_extension_fixed),
+	      "struct member likely outside of struct_group_tagged()");
 
  struct smc_clc_msg_proposal_prefix {	/* prefix part of clc proposal message*/
  	__be32 outgoing_subnet;	/* subnet mask */

@@ -169,6 +171,8 @@ struct smc_clc_smcd_v2_extension {
  	);
  	struct smc_clc_smcd_gid_chid gidchid[];
  };
+static_assert(offsetof(struct smc_clc_smcd_v2_extension, gidchid) == sizeof(struct smc_clc_smcd_v2_extension_fixed),
+	      "struct member likely outside of struct_group_tagged()");
 
  struct smc_clc_msg_proposal {	/* clc proposal message sent by Linux */
  	struct smc_clc_msg_hdr hdr;