flexible-array member convertion patches for 5.7-rc2

Hi Linus,
 
 Please, pull the following patches that replace zero-length arrays with
 flexible-array members.
 
 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 convertions) will also
 help to get completely rid of those sorts of issues.
 
 Notice that all of these patches have been baking in linux-next for
 quite a while now and, 238 more of these patches have already been
 merged into 5.7-rc1.
 
 There are a couple hundred more of these issues waiting to be addressed
 in the whole codebase.
 
 [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
 [2] https://github.com/KSPP/linux/issues/21
 [3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
 
 Thanks
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Merge tag 'flexible-array-member-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

Pull flexible-array member conversion from Gustavo Silva:
 "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
  convertions) will also help to get completely rid of those sorts of
  issues.

  Notice that all of these patches have been baking in linux-next for
  quite a while now and, 238 more of these patches have already been
  merged into 5.7-rc1.

  There are a couple hundred more of these issues waiting to be
  addressed in the whole codebase"

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

* tag 'flexible-array-member-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (28 commits)
  xattr.h: Replace zero-length array with flexible-array member
  uapi: linux: fiemap.h: Replace zero-length array with flexible-array member
  uapi: linux: dlm_device.h: Replace zero-length array with flexible-array member
  tpm_eventlog.h: Replace zero-length array with flexible-array member
  ti_wilink_st.h: Replace zero-length array with flexible-array member
  swap.h: Replace zero-length array with flexible-array member
  skbuff.h: Replace zero-length array with flexible-array member
  sched: topology.h: Replace zero-length array with flexible-array member
  rslib.h: Replace zero-length array with flexible-array member
  rio.h: Replace zero-length array with flexible-array member
  posix_acl.h: Replace zero-length array with flexible-array member
  platform_data: wilco-ec.h: Replace zero-length array with flexible-array member
  memcontrol.h: Replace zero-length array with flexible-array member
  list_lru.h: Replace zero-length array with flexible-array member
  lib: cpu_rmap: Replace zero-length array with flexible-array member
  irq.h: Replace zero-length array with flexible-array member
  ihex.h: Replace zero-length array with flexible-array member
  igmp.h: Replace zero-length array with flexible-array member
  genalloc.h: Replace zero-length array with flexible-array member
  ethtool.h: Replace zero-length array with flexible-array member
  ...

include/linux/bio.h

@@ -319,7 +319,7 @@ struct bio_integrity_payload {
 	struct work_struct	bip_work;	/* I/O completion */
 
 	struct bio_vec		*bip_vec;
-	struct bio_vec		bip_inline_vecs[0];/* embedded bvec array */
+	struct bio_vec		bip_inline_vecs[];/* embedded bvec array */
 };
 
 #if defined(CONFIG_BLK_DEV_INTEGRITY)

include/linux/blk-mq.h

@@ -173,7 +173,7 @@ struct blk_mq_hw_ctx {
 	 * blocking (BLK_MQ_F_BLOCKING). Must be the last member - see also
 	 * blk_mq_hw_ctx_size().
 	 */
-	struct srcu_struct	srcu[0];
+	struct srcu_struct	srcu[];
 };
 
 /**

include/linux/blk_types.h

@@ -198,7 +198,7 @@ struct bio {
 	 * double allocations for a small number of bio_vecs. This member
 	 * MUST obviously be kept at the very end of the bio.
 	 */
-	struct bio_vec		bi_inline_vecs[0];
+	struct bio_vec		bi_inline_vecs[];
 };
 
 #define BIO_RESET_BYTES		offsetof(struct bio, bi_max_vecs)

include/linux/can/dev/peak_canfd.h

@@ -189,7 +189,7 @@ struct __packed pucan_rx_msg {
 	u8	client;
 	__le16	flags;
 	__le32	can_id;
-	u8	d[0];
+	u8	d[];
 };
 
 /* uCAN error types */
@@ -266,7 +266,7 @@ struct __packed pucan_tx_msg {
 	u8	client;
 	__le16	flags;
 	__le32	can_id;
-	u8	d[0];
+	u8	d[];
 };
 
 /* build the cmd opcode_channel field with respect to the correct endianness */

include/linux/cpu_rmap.h

@@ -28,7 +28,7 @@ struct cpu_rmap {
 	struct {
 		u16	index;
 		u16	dist;
-	}		near[0];
+	}		near[];
 };
 #define CPU_RMAP_DIST_INF 0xffff
 

include/linux/digsig.h

@@ -29,7 +29,7 @@ struct pubkey_hdr {
 	uint32_t	timestamp;	/* key made, always 0 for now */
 	uint8_t		algo;
 	uint8_t		nmpi;
-	char		mpi[0];
+	char		mpi[];
 } __packed;
 
 struct signature_hdr {
@@ -39,7 +39,7 @@ struct signature_hdr {
 	uint8_t		hash;
 	uint8_t		keyid[8];
 	uint8_t		nmpi;
-	char		mpi[0];
+	char		mpi[];
 } __packed;
 
 #if defined(CONFIG_SIGNATURE) || defined(CONFIG_SIGNATURE_MODULE)

include/linux/dirent.h

@@ -7,7 +7,7 @@ struct linux_dirent64 {
 	s64		d_off;
 	unsigned short	d_reclen;
 	unsigned char	d_type;
-	char		d_name[0];
+	char		d_name[];
 };
 
 #endif

include/linux/enclosure.h

@@ -101,7 +101,7 @@ struct enclosure_device {
 	struct device edev;
 	struct enclosure_component_callbacks *cb;
 	int components;
-	struct enclosure_component component[0];
+	struct enclosure_component component[];
 };
 
 static inline struct enclosure_device *

include/linux/energy_model.h

@@ -36,7 +36,7 @@ struct em_cap_state {
 struct em_perf_domain {
 	struct em_cap_state *table;
 	int nr_cap_states;
-	unsigned long cpus[0];
+	unsigned long cpus[];
 };
 
 #ifdef CONFIG_ENERGY_MODEL

include/linux/ethtool.h

@@ -35,7 +35,7 @@ struct compat_ethtool_rxnfc {
 	compat_u64			data;
 	struct compat_ethtool_rx_flow_spec fs;
 	u32				rule_cnt;
-	u32				rule_locs[0];
+	u32				rule_locs[];
 };
 
 #endif /* CONFIG_COMPAT */
@@ -462,7 +462,7 @@ int ethtool_check_ops(const struct ethtool_ops *ops);
 
 struct ethtool_rx_flow_rule {
 	struct flow_rule	*rule;
-	unsigned long		priv[0];
+	unsigned long		priv[];
 };
 
 struct ethtool_rx_flow_spec_input {

include/linux/genalloc.h

@@ -76,7 +76,7 @@ struct gen_pool_chunk {
 	void *owner;			/* private data to retrieve at alloc time */
 	unsigned long start_addr;	/* start address of memory chunk */
 	unsigned long end_addr;		/* end address of memory chunk (inclusive) */
-	unsigned long bits[0];		/* bitmap for allocating memory chunk */
+	unsigned long bits[];		/* bitmap for allocating memory chunk */
 };
 
 /*

include/linux/igmp.h

@@ -38,7 +38,7 @@ struct ip_sf_socklist {
 	unsigned int		sl_max;
 	unsigned int		sl_count;
 	struct rcu_head		rcu;
-	__be32			sl_addr[0];
+	__be32			sl_addr[];
 };
 
 #define IP_SFLSIZE(count)	(sizeof(struct ip_sf_socklist) + \

include/linux/ihex.h

@@ -18,7 +18,7 @@
 struct ihex_binrec {
 	__be32 addr;
 	__be16 len;
-	uint8_t data[0];
+	uint8_t data[];
 } __attribute__((packed));
 
 static inline uint16_t ihex_binrec_size(const struct ihex_binrec *p)

include/linux/irq.h

@@ -1043,7 +1043,7 @@ struct irq_chip_generic {
 	unsigned long		unused;
 	struct irq_domain	*domain;
 	struct list_head	list;
-	struct irq_chip_type	chip_types[0];
+	struct irq_chip_type	chip_types[];
 };
 
 /**
@@ -1079,7 +1079,7 @@ struct irq_domain_chip_generic {
 	unsigned int		irq_flags_to_clear;
 	unsigned int		irq_flags_to_set;
 	enum irq_gc_flags	gc_flags;
-	struct irq_chip_generic	*gc[0];
+	struct irq_chip_generic	*gc[];
 };
 
 /* Generic chip callback functions */

include/linux/list_lru.h

@@ -34,7 +34,7 @@ struct list_lru_one {
 struct list_lru_memcg {
 	struct rcu_head		rcu;
 	/* array of per cgroup lists, indexed by memcg_cache_id */
-	struct list_lru_one	*lru[0];
+	struct list_lru_one	*lru[];
 };
 
 struct list_lru_node {

include/linux/memcontrol.h

@@ -106,7 +106,7 @@ struct lruvec_stat {
  */
 struct memcg_shrinker_map {
 	struct rcu_head rcu;
-	unsigned long map[0];
+	unsigned long map[];
 };
 
 /*
@@ -148,7 +148,7 @@ struct mem_cgroup_threshold_ary {
 	/* Size of entries[] */
 	unsigned int size;
 	/* Array of thresholds */
-	struct mem_cgroup_threshold entries[0];
+	struct mem_cgroup_threshold entries[];
 };
 
 struct mem_cgroup_thresholds {

include/linux/platform_data/wilco-ec.h

@@ -83,7 +83,7 @@ struct wilco_ec_response {
 	u16 result;
 	u16 data_size;
 	u8 reserved[2];
-	u8 data[0];
+	u8 data[];
 } __packed;
 
 /**

include/linux/posix_acl.h

@@ -28,7 +28,7 @@ struct posix_acl {
 	refcount_t		a_refcount;
 	struct rcu_head		a_rcu;
 	unsigned int		a_count;
-	struct posix_acl_entry	a_entries[0];
+	struct posix_acl_entry	a_entries[];
 };
 
 #define FOREACH_ACL_ENTRY(pa, acl, pe) \

include/linux/rio.h

@@ -100,7 +100,7 @@ struct rio_switch {
 	u32 port_ok;
 	struct rio_switch_ops *ops;
 	spinlock_t lock;
-	struct rio_dev *nextdev[0];
+	struct rio_dev *nextdev[];
 };
 
 /**
@@ -201,7 +201,7 @@ struct rio_dev {
 	u8 hopcount;
 	struct rio_dev *prev;
 	atomic_t state;
-	struct rio_switch rswitch[0];	/* RIO switch info */
+	struct rio_switch rswitch[];	/* RIO switch info */
 };
 
 #define rio_dev_g(n) list_entry(n, struct rio_dev, global_list)

include/linux/rslib.h

@@ -54,7 +54,7 @@ struct rs_codec {
  */
 struct rs_control {
 	struct rs_codec	*codec;
-	uint16_t	buffers[0];
+	uint16_t	buffers[];
 };
 
 /* General purpose RS codec, 8-bit data width, symbol width 1-15 bit  */

include/linux/sched/topology.h

@@ -142,7 +142,7 @@ struct sched_domain {
 	 * by attaching extra space to the end of the structure,
 	 * depending on how many CPUs the kernel has booted up with)
 	 */
-	unsigned long span[0];
+	unsigned long span[];
 };
 
 static inline struct cpumask *sched_domain_span(struct sched_domain *sd)

include/linux/skbuff.h

@@ -4162,7 +4162,7 @@ struct skb_ext {
 	refcount_t refcnt;
 	u8 offset[SKB_EXT_NUM]; /* in chunks of 8 bytes */
 	u8 chunks;		/* same */
-	char data[0] __aligned(8);
+	char data[] __aligned(8);
 };
 
 struct skb_ext *__skb_ext_alloc(void);

include/linux/swap.h

@@ -275,7 +275,7 @@ struct swap_info_struct {
 					 */
 	struct work_struct discard_work; /* discard worker */
 	struct swap_cluster_list discard_clusters; /* discard clusters list */
-	struct plist_node avail_lists[0]; /*
+	struct plist_node avail_lists[]; /*
 					   * entries in swap_avail_heads, one
 					   * entry per node.
 					   * Must be last as the number of the

include/linux/ti_wilink_st.h

@@ -295,7 +295,7 @@ struct bts_header {
 	u32 magic;
 	u32 version;
 	u8 future[24];
-	u8 actions[0];
+	u8 actions[];
 } __attribute__ ((packed));
 
 /**
@@ -305,7 +305,7 @@ struct bts_header {
 struct bts_action {
 	u16 type;
 	u16 size;
-	u8 data[0];
+	u8 data[];
 } __attribute__ ((packed));
 
 struct bts_action_send {
@@ -315,7 +315,7 @@ struct bts_action_send {
 struct bts_action_wait {
 	u32 msec;
 	u32 size;
-	u8 data[0];
+	u8 data[];
 } __attribute__ ((packed));
 
 struct bts_action_delay {

include/linux/tpm_eventlog.h

@@ -28,7 +28,7 @@ struct tcpa_event {
 	u32 event_type;
 	u8 pcr_value[20];	/* SHA1 */
 	u32 event_size;
-	u8 event_data[0];
+	u8 event_data[];
 };
 
 enum tcpa_event_types {
@@ -55,7 +55,7 @@ enum tcpa_event_types {
 struct tcpa_pc_event {
 	u32 event_id;
 	u32 event_size;
-	u8 event_data[0];
+	u8 event_data[];
 };
 
 enum tcpa_pc_event_ids {
@@ -102,7 +102,7 @@ struct tcg_pcr_event {
 
 struct tcg_event_field {
 	u32 event_size;
-	u8 event[0];
+	u8 event[];
 } __packed;
 
 struct tcg_pcr_event2_head {

include/linux/xattr.h

@@ -73,7 +73,7 @@ struct simple_xattr {
 	struct list_head list;
 	char *name;
 	size_t size;
-	char value[0];
+	char value[];
 };
 
 /*

include/uapi/linux/dlm_device.h

@@ -45,13 +45,13 @@ struct dlm_lock_params {
 	void __user *bastaddr;
 	struct dlm_lksb __user *lksb;
 	char lvb[DLM_USER_LVB_LEN];
-	char name[0];
+	char name[];
 };
 
 struct dlm_lspace_params {
 	__u32 flags;
 	__u32 minor;
-	char name[0];
+	char name[];
 };
 
 struct dlm_purge_params {

include/uapi/linux/fiemap.h

@@ -34,7 +34,7 @@ struct fiemap {
 	__u32 fm_mapped_extents;/* number of extents that were mapped (out) */
 	__u32 fm_extent_count;  /* size of fm_extents array (in) */
 	__u32 fm_reserved;
-	struct fiemap_extent fm_extents[0]; /* array of mapped extents (out) */
+	struct fiemap_extent fm_extents[]; /* array of mapped extents (out) */
 };
 
 #define FIEMAP_MAX_OFFSET	(~0ULL)