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 S. Miller <davem@davemloft.net>
u16 count;
u16 dglort;
struct rcu_head rcu;
- struct net_device *macvlan[0];
+ struct net_device *macvlan[];
};
enum fm10k_ring_state_t {
struct rcu_head rcu; /* to avoid race with update stats on free */
/* for dynamic allocation of rings associated with this q_vector */
- struct fm10k_ring ring[0] ____cacheline_internodealigned_in_smp;
+ struct fm10k_ring ring[] ____cacheline_internodealigned_in_smp;
};
enum fm10k_ring_f_enum {
unsigned int num_vfs;
unsigned int next_vf_mbx;
struct rcu_head rcu;
- struct fm10k_vf_info vf_info[0];
+ struct fm10k_vf_info vf_info[];
};
struct fm10k_udp_port {
struct i40e_ddp_profile_list {
u32 p_count;
- struct i40e_profile_info p_info[0];
+ struct i40e_profile_info p_info[];
};
struct i40e_ddp_old_profile_list {
struct list_head list;
size_t old_ddp_size;
- u8 old_ddp_buf[0];
+ u8 old_ddp_buf[];
};
/* macros related to FLX_PIT */
char name[IFNAMSIZ + 9];
/* for dynamic allocation of rings associated with this q_vector */
- struct igb_ring ring[0] ____cacheline_internodealigned_in_smp;
+ struct igb_ring ring[] ____cacheline_internodealigned_in_smp;
};
enum e1000_ring_flags_t {
struct net_device poll_dev;
/* for dynamic allocation of rings associated with this q_vector */
- struct igc_ring ring[0] ____cacheline_internodealigned_in_smp;
+ struct igc_ring ring[] ____cacheline_internodealigned_in_smp;
};
#define MAX_ETYPE_FILTER (4 - 1)
char name[IFNAMSIZ + 9];
/* for dynamic allocation of rings associated with this q_vector */
- struct ixgbe_ring ring[0] ____cacheline_internodealigned_in_smp;
+ struct ixgbe_ring ring[] ____cacheline_internodealigned_in_smp;
};
#ifdef CONFIG_IXGBE_HWMON