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>

5 files changed, 7 insertions, 7 deletions

diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 2d3e5df39a59..3974a2a911cc 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -1106,7 +1106,7 @@ struct snd_ctl_elem_value {
 struct snd_ctl_tlv {
 	unsigned int numid;	/* control element numeric identification */
 	unsigned int length;	/* in bytes aligned to 4 */
-	unsigned int tlv[0];	/* first TLV */
+	unsigned int tlv[];	/* first TLV */
 };
 
 #define SNDRV_CTL_IOCTL_PVERSION	_IOR('U', 0x00, int)
diff --git a/include/uapi/sound/firewire.h b/include/uapi/sound/firewire.h
index 39cf6eb75940..3532ac7046d7 100644
--- a/include/uapi/sound/firewire.h
+++ b/include/uapi/sound/firewire.h
@@ -38,11 +38,11 @@ struct snd_efw_transaction {
 	__be32 category;
 	__be32 command;
 	__be32 status;
-	__be32 params[0];
+	__be32 params[];
 };
 struct snd_firewire_event_efw_response {
 	unsigned int type;
-	__be32 response[0];	/* some responses */
+	__be32 response[];	/* some responses */
 };
 
 struct snd_firewire_event_digi00x_message {
@@ -63,7 +63,7 @@ struct snd_firewire_tascam_change {
 
 struct snd_firewire_event_tascam_control {
 	unsigned int type;
-	struct snd_firewire_tascam_change changes[0];
+	struct snd_firewire_tascam_change changes[];
 };
 
 struct snd_firewire_event_motu_register_dsp_change {
diff --git a/include/uapi/sound/skl-tplg-interface.h b/include/uapi/sound/skl-tplg-interface.h
index a93c0decfdd5..f29899b179a6 100644
--- a/include/uapi/sound/skl-tplg-interface.h
+++ b/include/uapi/sound/skl-tplg-interface.h
@@ -151,7 +151,7 @@ struct skl_dfw_algo_data {
 	__u32 rsvd:30;
 	__u32 param_id;
 	__u32 max;
-	char params[0];
+	char params[];
 } __packed;
 
 enum skl_tkn_dir {
diff --git a/include/uapi/sound/sof/header.h b/include/uapi/sound/sof/header.h
index 5f4518e7a972..dbf137516522 100644
--- a/include/uapi/sound/sof/header.h
+++ b/include/uapi/sound/sof/header.h
@@ -23,7 +23,7 @@ struct sof_abi_hdr {
 	__u32 size;		/**< size in bytes of data excl. this struct */
 	__u32 abi;		/**< SOF ABI version */
 	__u32 reserved[4];	/**< reserved for future use */
-	__u32 data[0];		/**< Component data - opaque to core */
+	__u32 data[];		/**< Component data - opaque to core */
 }  __packed;
 
 #endif
diff --git a/include/uapi/sound/usb_stream.h b/include/uapi/sound/usb_stream.h
index 95419d8bbc16..ffdd3ea1e31d 100644
--- a/include/uapi/sound/usb_stream.h
+++ b/include/uapi/sound/usb_stream.h
@@ -61,7 +61,7 @@ struct usb_stream {
 	unsigned		 inpacket_split_at;
 	unsigned		 next_inpacket_split;
 	unsigned		 next_inpacket_split_at;
-	struct usb_stream_packet inpacket[0];
+	struct usb_stream_packet inpacket[];
 };
 
 enum usb_stream_state {