Commit 040efdb1 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by David S. Miller
Browse files

intel: 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 76497732 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: default avatarGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3f6e9633

drivers/net/ethernet/intel/fm10k/fm10k.h

+3 −3
Original line number Diff line number Diff line
@@ -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 {

drivers/net/ethernet/intel/i40e/i40e.h

+2 −2
Original line number Diff line number Diff line
@@ -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 */

drivers/net/ethernet/intel/igb/igb.h

+1 −1
Original line number Diff line number Diff line
@@ -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 {

drivers/net/ethernet/intel/igc/igc.h

+1 −1
Original line number Diff line number Diff line
@@ -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)

drivers/net/ethernet/intel/ixgbe/ixgbe.h

+1 −1
Original line number Diff line number Diff line
@@ -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

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