treewide: uapi: Replace zero-length arrays with flexible-array members

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

This code was transformed with the help of Coccinelle:
(linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

@@
identifier S, member, array;
type T1, T2;
@@

struct S {
  ...
  T1 member;
  T2 array[
- 0
  ];
};

-fstrict-flex-arrays=3 is coming and we need to land these changes
to prevent issues like these in the short future:

../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0,
but the source string has length 2 (including NUL byte) [-Wfortify-source]
		strcpy(de3->name, ".");
		^

Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If
this breaks anything, we can use a union with a new member name.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/62b675ec.wKX6AOZ6cbE71vtF%25lkp@intel.com/
Acked-by: Dan Williams <dan.j.williams@intel.com> # For ndctl.h
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

1 files changed, 14 insertions, 14 deletions

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index e0f0ee9bc89e..2d5741fd44bb 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -257,7 +257,7 @@ struct ethtool_tunable {
 	__u32	id;
 	__u32	type_id;
 	__u32	len;
-	void	*data[0];
+	void	*data[];
 };
 
 #define DOWNSHIFT_DEV_DEFAULT_COUNT	0xff
@@ -322,7 +322,7 @@ struct ethtool_regs {
 	__u32	cmd;
 	__u32	version;
 	__u32	len;
-	__u8	data[0];
+	__u8	data[];
 };
 
 /**
@@ -348,7 +348,7 @@ struct ethtool_eeprom {
 	__u32	magic;
 	__u32	offset;
 	__u32	len;
-	__u8	data[0];
+	__u8	data[];
 };
 
 /**
@@ -752,7 +752,7 @@ struct ethtool_gstrings {
 	__u32	cmd;
 	__u32	string_set;
 	__u32	len;
-	__u8	data[0];
+	__u8	data[];
 };
 
 /**
@@ -777,7 +777,7 @@ struct ethtool_sset_info {
 	__u32	cmd;
 	__u32	reserved;
 	__u64	sset_mask;
-	__u32	data[0];
+	__u32	data[];
 };
 
 /**
@@ -817,7 +817,7 @@ struct ethtool_test {
 	__u32	flags;
 	__u32	reserved;
 	__u32	len;
-	__u64	data[0];
+	__u64	data[];
 };
 
 /**
@@ -834,7 +834,7 @@ struct ethtool_test {
 struct ethtool_stats {
 	__u32	cmd;
 	__u32	n_stats;
-	__u64	data[0];
+	__u64	data[];
 };
 
 /**
@@ -851,7 +851,7 @@ struct ethtool_stats {
 struct ethtool_perm_addr {
 	__u32	cmd;
 	__u32	size;
-	__u8	data[0];
+	__u8	data[];
 };
 
 /* boolean flags controlling per-interface behavior characteristics.
@@ -1160,7 +1160,7 @@ struct ethtool_rxnfc {
 struct ethtool_rxfh_indir {
 	__u32	cmd;
 	__u32	size;
-	__u32	ring_index[0];
+	__u32	ring_index[];
 };
 
 /**
@@ -1201,7 +1201,7 @@ struct ethtool_rxfh {
 	__u8	hfunc;
 	__u8	rsvd8[3];
 	__u32	rsvd32;
-	__u32   rss_config[0];
+	__u32   rss_config[];
 };
 #define ETH_RXFH_CONTEXT_ALLOC		0xffffffff
 #define ETH_RXFH_INDIR_NO_CHANGE	0xffffffff
@@ -1286,7 +1286,7 @@ struct ethtool_dump {
 	__u32	version;
 	__u32	flag;
 	__u32	len;
-	__u8	data[0];
+	__u8	data[];
 };
 
 #define ETH_FW_DUMP_DISABLE 0
@@ -1318,7 +1318,7 @@ struct ethtool_get_features_block {
 struct ethtool_gfeatures {
 	__u32	cmd;
 	__u32	size;
-	struct ethtool_get_features_block features[0];
+	struct ethtool_get_features_block features[];
 };
 
 /**
@@ -1340,7 +1340,7 @@ struct ethtool_set_features_block {
 struct ethtool_sfeatures {
 	__u32	cmd;
 	__u32	size;
-	struct ethtool_set_features_block features[0];
+	struct ethtool_set_features_block features[];
 };
 
 /**
@@ -2087,7 +2087,7 @@ struct ethtool_link_settings {
 	__u8	master_slave_state;
 	__u8	reserved1[1];
 	__u32	reserved[7];
-	__u32	link_mode_masks[0];
+	__u32	link_mode_masks[];
 	/* layout of link_mode_masks fields:
 	 * __u32 map_supported[link_mode_masks_nwords];
 	 * __u32 map_advertising[link_mode_masks_nwords];