[Intel-wired-lan] [PATCH][next] intel: Replace zero-length array with flexible-array member
Gustavo A. R. Silva
gustavo at embeddedor.com
Mon Feb 24 16:41:06 UTC 2020
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 at embeddedor.com>
---
drivers/net/ethernet/intel/fm10k/fm10k.h | 6 +++---
drivers/net/ethernet/intel/i40e/i40e.h | 4 ++--
drivers/net/ethernet/intel/igb/igb.h | 2 +-
drivers/net/ethernet/intel/igc/igc.h | 2 +-
drivers/net/ethernet/intel/ixgbe/ixgbe.h | 2 +-
5 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/net/ethernet/intel/fm10k/fm10k.h b/drivers/net/ethernet/intel/fm10k/fm10k.h
index f306084ca12c..5b78362b82ac 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k.h
+++ b/drivers/net/ethernet/intel/fm10k/fm10k.h
@@ -41,7 +41,7 @@ struct fm10k_l2_accel {
u16 count;
u16 dglort;
struct rcu_head rcu;
- struct net_device *macvlan[0];
+ struct net_device *macvlan[];
};
enum fm10k_ring_state_t {
@@ -198,7 +198,7 @@ struct fm10k_q_vector {
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 {
@@ -218,7 +218,7 @@ struct fm10k_iov_data {
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 {
diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 4833187bd259..e95b8da45e07 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -334,13 +334,13 @@ int i40e_ddp_flash(struct net_device *netdev, struct ethtool_flash *flash);
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 */
diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
index 49b5fa9d4783..0c9282e2aaec 100644
--- a/drivers/net/ethernet/intel/igb/igb.h
+++ b/drivers/net/ethernet/intel/igb/igb.h
@@ -306,7 +306,7 @@ struct igb_q_vector {
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 {
diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index 0014828eec46..a1f845a2aa80 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -326,7 +326,7 @@ struct igc_q_vector {
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)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index 39e73ad60352..2833e4f041ce 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -462,7 +462,7 @@ struct ixgbe_q_vector {
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
--
2.25.0
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