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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 22:23:02 +0300
committerDavid S. Miller <davem@davemloft.net>2020-05-08 04:49:04 +0300
commit60da7d0bc7482a30817c73fdc8152123d19919f8 (patch)
tree7072d1e19f93bc4a7c4a6d565b239d8707f203eb /arch
parent57829ea46875770c919ae491dcabf4e2aa5cb385 (diff)
downloadlinux-60da7d0bc7482a30817c73fdc8152123d19919f8.tar.xz
sparc64: Replace zero-length array with flexible-array
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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. 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 <gustavoars@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch')
-rw-r--r--arch/sparc/kernel/cpumap.c2
-rw-r--r--arch/sparc/kernel/ds.c8
2 files changed, 5 insertions, 5 deletions
diff --git a/arch/sparc/kernel/cpumap.c b/arch/sparc/kernel/cpumap.c
index 1cb62bfeaa1f..f07ea88a83af 100644
--- a/arch/sparc/kernel/cpumap.c
+++ b/arch/sparc/kernel/cpumap.c
@@ -50,7 +50,7 @@ struct cpuinfo_tree {
/* Offsets into nodes[] for each level of the tree */
struct cpuinfo_level level[CPUINFO_LVL_MAX];
- struct cpuinfo_node nodes[0];
+ struct cpuinfo_node nodes[];
};
diff --git a/arch/sparc/kernel/ds.c b/arch/sparc/kernel/ds.c
index 75232cbd58bf..522e5b51050c 100644
--- a/arch/sparc/kernel/ds.c
+++ b/arch/sparc/kernel/ds.c
@@ -87,7 +87,7 @@ struct ds_reg_req {
__u64 handle;
__u16 major;
__u16 minor;
- char svc_id[0];
+ char svc_id[];
};
struct ds_reg_ack {
@@ -701,12 +701,12 @@ struct ds_var_hdr {
struct ds_var_set_msg {
struct ds_var_hdr hdr;
- char name_and_value[0];
+ char name_and_value[];
};
struct ds_var_delete_msg {
struct ds_var_hdr hdr;
- char name[0];
+ char name[];
};
struct ds_var_resp {
@@ -989,7 +989,7 @@ struct ds_queue_entry {
struct ds_info *dp;
int req_len;
int __pad;
- u64 req[0];
+ u64 req[];
};
static void process_ds_work(void)