On 2024/3/13 01:55, Gustavo A. R. Silva wrote:
-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.
There are currently a couple of objects in `struct smc_clc_msg_proposal_area`
that contain a couple of flexible structures:
struct smc_clc_msg_proposal_area {
...
struct smc_clc_v2_extension pclc_v2_ext;
...
struct smc_clc_smcd_v2_extension pclc_smcd_v2_ext;
...
};
So, in order to avoid ending up with a couple of flexible-array members
in the middle of a struct, we use the `struct_group_tagged()` helper to
separate the flexible array from the rest of the members in the flexible
structure:
struct smc_clc_smcd_v2_extension {
struct_group_tagged(smc_clc_smcd_v2_extension_fixed, fixed,
u8 system_eid[SMC_MAX_EID_LEN];
u8 reserved[16];
);
struct smc_clc_smcd_gid_chid gidchid[];
};
With the change described above, we now declare objects of the type of
the tagged struct without embedding flexible arrays in the middle of
another struct:
struct smc_clc_msg_proposal_area {
...
struct smc_clc_v2_extension_fixed pclc_v2_ext;
...
struct smc_clc_smcd_v2_extension_fixed pclc_smcd_v2_ext;
...
};
We also use `container_of()` when we need to retrieve a pointer to the
flexible structures.
So, with these changes, fix the following warnings:
In file included from net/smc/af_smc.c:42:
net/smc/smc_clc.h:186:49: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
186 | struct smc_clc_v2_extension pclc_v2_ext;
| ^~~~~~~~~~~
net/smc/smc_clc.h:188:49: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
188 | struct smc_clc_smcd_v2_extension pclc_smcd_v2_ext;
| ^~~~~~~~~~~~~~~~
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Hi Gustavo,
Thank you for the v2. Some places may need improvement, see below.
---
Changes in v2:
- Name the tagged struct *_fixed instead of *_hdr.
- Add Kees' RB tag.
net/smc/smc_clc.c | 5 +++--
net/smc/smc_clc.h | 24 ++++++++++++++----------
2 files changed, 17 insertions(+), 12 deletions(-)
diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
index e55026c7529c..63bb5745ab54 100644
--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -853,8 +853,9 @@ int smc_clc_send_proposal(struct smc_sock *smc, struct smc_init_info *ini)
pclc_smcd = &pclc->pclc_smcd;
pclc_prfx = &pclc->pclc_prfx;
ipv6_prfx = pclc->pclc_prfx_ipv6;
- v2_ext = &pclc->pclc_v2_ext;
- smcd_v2_ext = &pclc->pclc_smcd_v2_ext;
+ v2_ext = container_of(&pclc->pclc_v2_ext, struct smc_clc_v2_extension, fixed);
checkpatch complained 'WARNING: line length of 86 exceeds 80 columns' here.
It can be reproduced by:
./scripts/checkpatch.pl --strict --max-line-length=80
--ignore=COMMIT_LOG_LONG_LINE,MACRO_ARG_REUSE,ALLOC_SIZEOF_STRUCT,NO_AUTHOR_SIGN_OFF,GIT_COMMIT_ID,CAMELCASE xxx.patch
+ smcd_v2_ext = container_of(&pclc->pclc_smcd_v2_ext,
+ struct smc_clc_smcd_v2_extension, fixed);
gidchids = pclc->pclc_gidchids;
trl = &pclc->pclc_trl;
diff --git a/net/smc/smc_clc.h b/net/smc/smc_clc.h
index 7cc7070b9772..2bfb51daf468 100644
--- a/net/smc/smc_clc.h
+++ b/net/smc/smc_clc.h
@@ -134,12 +134,14 @@ struct smc_clc_smcd_gid_chid {
*/
struct smc_clc_v2_extension {
- struct smc_clnt_opts_area_hdr hdr;
- u8 roce[16]; /* RoCEv2 GID */
- u8 max_conns;
- u8 max_links;
- __be16 feature_mask;
- u8 reserved[12];
+ struct_group_tagged(smc_clc_v2_extension_fixed, fixed,
+ struct smc_clnt_opts_area_hdr hdr;
checkpatch: 'CHECK: Alignment should match open parenthesis'
+ u8 roce[16]; /* RoCEv2 GID */
+ u8 max_conns;
+ u8 max_links;
+ __be16 feature_mask;
+ u8 reserved[12];
+ );
u8 user_eids[][SMC_MAX_EID_LEN];
};
@@ -159,8 +161,10 @@ struct smc_clc_msg_smcd { /* SMC-D GID information */
};
struct smc_clc_smcd_v2_extension {
- u8 system_eid[SMC_MAX_EID_LEN];
- u8 reserved[16];
+ struct_group_tagged(smc_clc_smcd_v2_extension_fixed, fixed,
+ u8 system_eid[SMC_MAX_EID_LEN];
checkpatch: 'CHECK: Alignment should match open parenthesis'
Thanks!
Wen Gu
+ u8 reserved[16];
+ );
struct smc_clc_smcd_gid_chid gidchid[];
};
@@ -183,9 +187,9 @@ struct smc_clc_msg_proposal_area {
struct smc_clc_msg_smcd pclc_smcd;
struct smc_clc_msg_proposal_prefix pclc_prfx;
struct smc_clc_ipv6_prefix pclc_prfx_ipv6[SMC_CLC_MAX_V6_PREFIX];
- struct smc_clc_v2_extension pclc_v2_ext;
+ struct smc_clc_v2_extension_fixed pclc_v2_ext;
u8 user_eids[SMC_CLC_MAX_UEID][SMC_MAX_EID_LEN];
- struct smc_clc_smcd_v2_extension pclc_smcd_v2_ext;
+ struct smc_clc_smcd_v2_extension_fixed pclc_smcd_v2_ext;
struct smc_clc_smcd_gid_chid
pclc_gidchids[SMCD_CLC_MAX_V2_GID_ENTRIES];
struct smc_clc_msg_trail pclc_trl;
