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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-09 10:56:08 -0500
committerDavid Teigland <teigland@redhat.com>2020-05-12 14:06:14 -0500
commita4e439a6f628a52f7074c9d73ec7eb4f6c1a4dfc (patch)
tree7545882bd15e3a31f12ac1359d973ed892bb99af /fs/dlm
parent1d2cc5ac6f6668cc15216d51051103c61467d7e8 (diff)
downloadlinux-a4e439a6f628a52f7074c9d73ec7eb4f6c1a4dfc.tar.bz2
dlm: dlm_internal: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: David Teigland <teigland@redhat.com>
Diffstat (limited to 'fs/dlm')
-rw-r--r--fs/dlm/dlm_internal.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index 416d9de35679..d231ae5d2c65 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -421,7 +421,7 @@ struct dlm_message {
int m_bastmode;
int m_asts;
int m_result; /* 0 or -EXXX */
- char m_extra[0]; /* name or lvb */
+ char m_extra[]; /* name or lvb */
};
@@ -450,7 +450,7 @@ struct dlm_rcom {
uint64_t rc_id; /* match reply with request */
uint64_t rc_seq; /* sender's ls_recover_seq */
uint64_t rc_seq_reply; /* remote ls_recover_seq */
- char rc_buf[0];
+ char rc_buf[];
};
union dlm_packet {
@@ -506,7 +506,7 @@ struct rcom_lock {
__le16 rl_wait_type;
__le16 rl_namelen;
char rl_name[DLM_RESNAME_MAXLEN];
- char rl_lvb[0];
+ char rl_lvb[];
};
/*