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Re: [PATCH v2 1/2] misc: Replace zero-length arrays with flexible array
|
From: |
Michael S. Tsirkin |
|
Subject: |
Re: [PATCH v2 1/2] misc: Replace zero-length arrays with flexible array member (automatic) |
|
Date: |
Sun, 8 Mar 2020 03:55:28 -0400 |
On Wed, Mar 04, 2020 at 04:38:15PM +0100, Philippe Mathieu-Daudé wrote:
> Description copied from Linux kernel commit from Gustavo A. R. Silva
> (see [3]):
>
> --v-- description start --v--
>
> 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], 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 unadvertenly introduced [2] to the
> Linux codebase from now on.
>
> --^-- description end --^--
>
> Do the similar housekeeping in the QEMU codebase (which uses
> C99 since commit 7be41675f7cb).
>
> All these instances of code were found with the help of the
> following Coccinelle script:
>
> @@
> identifier s, m, a;
> type t, T;
> @@
> struct s {
> ...
> t m;
> - T a[0];
> + T a[];
> };
> @@
> identifier s, m, a;
> type t, T;
> @@
> struct s {
> ...
> t m;
> - T a[0];
> + T a[];
> } QEMU_PACKED;
>
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76497732932f
> [3]
> https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git/commit/?id=17642a2fbd2c1
>
> Inspired-by: Gustavo A. R. Silva <address@hidden>
> Reviewed-by: David Hildenbrand <address@hidden>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
Acked-by: Michael S. Tsirkin <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
> ---
> v2: cocci script updated to not match structures of onlyi
> a single flexible array member:
>
> block/qed.h:106:14: error: flexible array member 'offsets' not allowed in
> otherwise empty struct
> uint64_t offsets[]; /* in bytes */
> ^
> ---
> bsd-user/qemu.h | 2 +-
> contrib/libvhost-user/libvhost-user.h | 2 +-
> hw/m68k/bootinfo.h | 2 +-
> hw/scsi/srp.h | 6 +++---
> hw/xen/xen_pt.h | 2 +-
> include/hw/acpi/acpi-defs.h | 12 ++++++------
> include/hw/arm/smmu-common.h | 2 +-
> include/hw/i386/intel_iommu.h | 3 ++-
> include/hw/virtio/virtio-iommu.h | 2 +-
> include/sysemu/cryptodev.h | 2 +-
> include/tcg/tcg.h | 2 +-
> pc-bios/s390-ccw/bootmap.h | 2 +-
> pc-bios/s390-ccw/sclp.h | 2 +-
> tests/qtest/libqos/ahci.h | 2 +-
> block/linux-aio.c | 2 +-
> hw/acpi/nvdimm.c | 6 +++---
> hw/dma/soc_dma.c | 2 +-
> hw/i386/x86.c | 2 +-
> hw/misc/omap_l4.c | 2 +-
> hw/nvram/eeprom93xx.c | 2 +-
> hw/rdma/vmw/pvrdma_qp_ops.c | 4 ++--
> hw/usb/dev-network.c | 2 +-
> hw/usb/dev-smartcard-reader.c | 4 ++--
> hw/virtio/virtio.c | 4 ++--
> net/queue.c | 2 +-
> 25 files changed, 38 insertions(+), 37 deletions(-)
>
> diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h
> index 09e8aed9c7..f8bb1e5459 100644
> --- a/bsd-user/qemu.h
> +++ b/bsd-user/qemu.h
> @@ -95,7 +95,7 @@ typedef struct TaskState {
> struct sigqueue *first_free; /* first free siginfo queue entry */
> int signal_pending; /* non zero if a signal may be pending */
>
> - uint8_t stack[0];
> + uint8_t stack[];
> } __attribute__((aligned(16))) TaskState;
>
> void init_task_state(TaskState *ts);
> diff --git a/contrib/libvhost-user/libvhost-user.h
> b/contrib/libvhost-user/libvhost-user.h
> index 6fc8000e99..f30394fab6 100644
> --- a/contrib/libvhost-user/libvhost-user.h
> +++ b/contrib/libvhost-user/libvhost-user.h
> @@ -286,7 +286,7 @@ typedef struct VuVirtqInflight {
> uint16_t used_idx;
>
> /* Used to track the state of each descriptor in descriptor table */
> - VuDescStateSplit desc[0];
> + VuDescStateSplit desc[];
> } VuVirtqInflight;
>
> typedef struct VuVirtqInflightDesc {
> diff --git a/hw/m68k/bootinfo.h b/hw/m68k/bootinfo.h
> index 5f8ded2686..c954270aad 100644
> --- a/hw/m68k/bootinfo.h
> +++ b/hw/m68k/bootinfo.h
> @@ -14,7 +14,7 @@
> struct bi_record {
> uint16_t tag; /* tag ID */
> uint16_t size; /* size of record */
> - uint32_t data[0]; /* data */
> + uint32_t data[]; /* data */
> };
>
> /* machine independent tags */
> diff --git a/hw/scsi/srp.h b/hw/scsi/srp.h
> index d27f31d2d5..54c954badd 100644
> --- a/hw/scsi/srp.h
> +++ b/hw/scsi/srp.h
> @@ -112,7 +112,7 @@ struct srp_direct_buf {
> struct srp_indirect_buf {
> struct srp_direct_buf table_desc;
> uint32_t len;
> - struct srp_direct_buf desc_list[0];
> + struct srp_direct_buf desc_list[];
> } QEMU_PACKED;
>
> enum {
> @@ -211,7 +211,7 @@ struct srp_cmd {
> uint8_t reserved4;
> uint8_t add_cdb_len;
> uint8_t cdb[16];
> - uint8_t add_data[0];
> + uint8_t add_data[];
> } QEMU_PACKED;
>
> enum {
> @@ -241,7 +241,7 @@ struct srp_rsp {
> uint32_t data_in_res_cnt;
> uint32_t sense_data_len;
> uint32_t resp_data_len;
> - uint8_t data[0];
> + uint8_t data[];
> } QEMU_PACKED;
>
> #endif /* SCSI_SRP_H */
> diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
> index 9167bbaf6d..179775db7b 100644
> --- a/hw/xen/xen_pt.h
> +++ b/hw/xen/xen_pt.h
> @@ -203,7 +203,7 @@ typedef struct XenPTMSIX {
> uint64_t mmio_base_addr;
> MemoryRegion mmio;
> void *phys_iomem_base;
> - XenPTMSIXEntry msix_entry[0];
> + XenPTMSIXEntry msix_entry[];
> } XenPTMSIX;
>
> struct XenPCIPassthroughState {
> diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
> index 57a3f58b0c..19f7ba7b70 100644
> --- a/include/hw/acpi/acpi-defs.h
> +++ b/include/hw/acpi/acpi-defs.h
> @@ -518,7 +518,7 @@ struct AcpiDmarDeviceScope {
> struct {
> uint8_t device;
> uint8_t function;
> - } path[0];
> + } path[];
> } QEMU_PACKED;
> typedef struct AcpiDmarDeviceScope AcpiDmarDeviceScope;
>
> @@ -530,7 +530,7 @@ struct AcpiDmarHardwareUnit {
> uint8_t reserved;
> uint16_t pci_segment; /* The PCI Segment associated with this unit */
> uint64_t address; /* Base address of remapping hardware register-set */
> - AcpiDmarDeviceScope scope[0];
> + AcpiDmarDeviceScope scope[];
> } QEMU_PACKED;
> typedef struct AcpiDmarHardwareUnit AcpiDmarHardwareUnit;
>
> @@ -541,7 +541,7 @@ struct AcpiDmarRootPortATS {
> uint8_t flags;
> uint8_t reserved;
> uint16_t pci_segment;
> - AcpiDmarDeviceScope scope[0];
> + AcpiDmarDeviceScope scope[];
> } QEMU_PACKED;
> typedef struct AcpiDmarRootPortATS AcpiDmarRootPortATS;
>
> @@ -604,7 +604,7 @@ typedef struct AcpiIortMemoryAccess AcpiIortMemoryAccess;
> struct AcpiIortItsGroup {
> ACPI_IORT_NODE_HEADER_DEF
> uint32_t its_count;
> - uint32_t identifiers[0];
> + uint32_t identifiers[];
> } QEMU_PACKED;
> typedef struct AcpiIortItsGroup AcpiIortItsGroup;
>
> @@ -621,7 +621,7 @@ struct AcpiIortSmmu3 {
> uint32_t pri_gsiv;
> uint32_t gerr_gsiv;
> uint32_t sync_gsiv;
> - AcpiIortIdMapping id_mapping_array[0];
> + AcpiIortIdMapping id_mapping_array[];
> } QEMU_PACKED;
> typedef struct AcpiIortSmmu3 AcpiIortSmmu3;
>
> @@ -630,7 +630,7 @@ struct AcpiIortRC {
> AcpiIortMemoryAccess memory_properties;
> uint32_t ats_attribute;
> uint32_t pci_segment_number;
> - AcpiIortIdMapping id_mapping_array[0];
> + AcpiIortIdMapping id_mapping_array[];
> } QEMU_PACKED;
> typedef struct AcpiIortRC AcpiIortRC;
>
> diff --git a/include/hw/arm/smmu-common.h b/include/hw/arm/smmu-common.h
> index 1f37844e5c..ca4a4b1ad1 100644
> --- a/include/hw/arm/smmu-common.h
> +++ b/include/hw/arm/smmu-common.h
> @@ -85,7 +85,7 @@ typedef struct SMMUDevice {
>
> typedef struct SMMUPciBus {
> PCIBus *bus;
> - SMMUDevice *pbdev[0]; /* Parent array is sparse, so dynamically alloc
> */
> + SMMUDevice *pbdev[]; /* Parent array is sparse, so dynamically alloc */
> } SMMUPciBus;
>
> typedef struct SMMUIOTLBKey {
> diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
> index 66b931e526..67aaa64c1b 100644
> --- a/include/hw/i386/intel_iommu.h
> +++ b/include/hw/i386/intel_iommu.h
> @@ -118,7 +118,8 @@ struct VTDAddressSpace {
>
> struct VTDBus {
> PCIBus* bus; /* A reference to the bus to provide
> translation for */
> - VTDAddressSpace *dev_as[0]; /* A table of VTDAddressSpace objects
> indexed by devfn */
> + /* A table of VTDAddressSpace objects indexed by devfn */
> + VTDAddressSpace *dev_as[];
> };
>
> struct VTDIOTLBEntry {
> diff --git a/include/hw/virtio/virtio-iommu.h
> b/include/hw/virtio/virtio-iommu.h
> index 6f67f1020a..e653004d7c 100644
> --- a/include/hw/virtio/virtio-iommu.h
> +++ b/include/hw/virtio/virtio-iommu.h
> @@ -41,7 +41,7 @@ typedef struct IOMMUDevice {
>
> typedef struct IOMMUPciBus {
> PCIBus *bus;
> - IOMMUDevice *pbdev[0]; /* Parent array is sparse, so dynamically alloc
> */
> + IOMMUDevice *pbdev[]; /* Parent array is sparse, so dynamically alloc */
> } IOMMUPciBus;
>
> typedef struct VirtIOIOMMU {
> diff --git a/include/sysemu/cryptodev.h b/include/sysemu/cryptodev.h
> index a9afb7e5b5..35eab06d0e 100644
> --- a/include/sysemu/cryptodev.h
> +++ b/include/sysemu/cryptodev.h
> @@ -143,7 +143,7 @@ typedef struct CryptoDevBackendSymOpInfo {
> uint8_t *dst;
> uint8_t *aad_data;
> uint8_t *digest_result;
> - uint8_t data[0];
> + uint8_t data[];
> } CryptoDevBackendSymOpInfo;
>
> typedef struct CryptoDevBackendClass {
> diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h
> index 54e5446880..c48bd76b0a 100644
> --- a/include/tcg/tcg.h
> +++ b/include/tcg/tcg.h
> @@ -267,7 +267,7 @@ struct TCGLabel {
> typedef struct TCGPool {
> struct TCGPool *next;
> int size;
> - uint8_t data[0] __attribute__ ((aligned));
> + uint8_t data[] __attribute__ ((aligned));
> } TCGPool;
>
> #define TCG_POOL_CHUNK_SIZE 32768
> diff --git a/pc-bios/s390-ccw/bootmap.h b/pc-bios/s390-ccw/bootmap.h
> index 94f53a5f1e..12a0166aae 100644
> --- a/pc-bios/s390-ccw/bootmap.h
> +++ b/pc-bios/s390-ccw/bootmap.h
> @@ -136,7 +136,7 @@ typedef struct BootMapScriptHeader {
>
> typedef struct BootMapScript {
> BootMapScriptHeader header;
> - BootMapScriptEntry entry[0];
> + BootMapScriptEntry entry[];
> } __attribute__ ((packed)) BootMapScript;
>
> /*
> diff --git a/pc-bios/s390-ccw/sclp.h b/pc-bios/s390-ccw/sclp.h
> index 8450161ba7..64b53cad29 100644
> --- a/pc-bios/s390-ccw/sclp.h
> +++ b/pc-bios/s390-ccw/sclp.h
> @@ -95,7 +95,7 @@ typedef struct EventBufferHeader {
> typedef struct WriteEventData {
> SCCBHeader h;
> EventBufferHeader ebh;
> - char data[0];
> + char data[];
> } __attribute__((packed)) WriteEventData;
>
> typedef struct ReadEventData {
> diff --git a/tests/qtest/libqos/ahci.h b/tests/qtest/libqos/ahci.h
> index f05b3e5fce..44ab1104b5 100644
> --- a/tests/qtest/libqos/ahci.h
> +++ b/tests/qtest/libqos/ahci.h
> @@ -351,7 +351,7 @@ typedef struct AHCIQState {
> typedef struct FIS {
> uint8_t fis_type;
> uint8_t flags;
> - char data[0];
> + char data[];
> } __attribute__((__packed__)) FIS;
>
> /**
> diff --git a/block/linux-aio.c b/block/linux-aio.c
> index 91204a25a2..3c0527c2bf 100644
> --- a/block/linux-aio.c
> +++ b/block/linux-aio.c
> @@ -121,7 +121,7 @@ struct aio_ring {
> unsigned incompat_features;
> unsigned header_length; /* size of aio_ring */
>
> - struct io_event io_events[0];
> + struct io_event io_events[];
> };
>
> /**
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index 5219dd0e2e..eb6a37b14e 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -485,7 +485,7 @@ struct NvdimmFuncGetLabelDataOut {
> /* the size of buffer filled by QEMU. */
> uint32_t len;
> uint32_t func_ret_status; /* return status code. */
> - uint8_t out_buf[0]; /* the data got via Get Namesapce Label function. */
> + uint8_t out_buf[]; /* the data got via Get Namesapce Label function. */
> } QEMU_PACKED;
> typedef struct NvdimmFuncGetLabelDataOut NvdimmFuncGetLabelDataOut;
> QEMU_BUILD_BUG_ON(sizeof(NvdimmFuncGetLabelDataOut) >
> NVDIMM_DSM_MEMORY_SIZE);
> @@ -493,7 +493,7 @@ QEMU_BUILD_BUG_ON(sizeof(NvdimmFuncGetLabelDataOut) >
> NVDIMM_DSM_MEMORY_SIZE);
> struct NvdimmFuncSetLabelDataIn {
> uint32_t offset; /* the offset in the namespace label data area. */
> uint32_t length; /* the size of data is to be written via the function.
> */
> - uint8_t in_buf[0]; /* the data written to label data area. */
> + uint8_t in_buf[]; /* the data written to label data area. */
> } QEMU_PACKED;
> typedef struct NvdimmFuncSetLabelDataIn NvdimmFuncSetLabelDataIn;
> QEMU_BUILD_BUG_ON(sizeof(NvdimmFuncSetLabelDataIn) +
> @@ -510,7 +510,7 @@ struct NvdimmFuncReadFITOut {
> /* the size of buffer filled by QEMU. */
> uint32_t len;
> uint32_t func_ret_status; /* return status code. */
> - uint8_t fit[0]; /* the FIT data. */
> + uint8_t fit[]; /* the FIT data. */
> } QEMU_PACKED;
> typedef struct NvdimmFuncReadFITOut NvdimmFuncReadFITOut;
> QEMU_BUILD_BUG_ON(sizeof(NvdimmFuncReadFITOut) > NVDIMM_DSM_MEMORY_SIZE);
> diff --git a/hw/dma/soc_dma.c b/hw/dma/soc_dma.c
> index c3e41581b6..3a430057f5 100644
> --- a/hw/dma/soc_dma.c
> +++ b/hw/dma/soc_dma.c
> @@ -80,7 +80,7 @@ struct dma_s {
> } *memmap;
> int memmap_size;
>
> - struct soc_dma_ch_s ch[0];
> + struct soc_dma_ch_s ch[];
> };
>
> static void soc_dma_ch_schedule(struct soc_dma_ch_s *ch, int delay_bytes)
> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
> index 7f38e6ba8b..08246523f2 100644
> --- a/hw/i386/x86.c
> +++ b/hw/i386/x86.c
> @@ -328,7 +328,7 @@ struct setup_data {
> uint64_t next;
> uint32_t type;
> uint32_t len;
> - uint8_t data[0];
> + uint8_t data[];
> } __attribute__((packed));
>
>
> diff --git a/hw/misc/omap_l4.c b/hw/misc/omap_l4.c
> index 61b6df564a..54aeaecd69 100644
> --- a/hw/misc/omap_l4.c
> +++ b/hw/misc/omap_l4.c
> @@ -24,7 +24,7 @@ struct omap_l4_s {
> MemoryRegion *address_space;
> hwaddr base;
> int ta_num;
> - struct omap_target_agent_s ta[0];
> + struct omap_target_agent_s ta[];
> };
>
> struct omap_l4_s *omap_l4_init(MemoryRegion *address_space,
> diff --git a/hw/nvram/eeprom93xx.c b/hw/nvram/eeprom93xx.c
> index 07f09549ed..ca6f591c84 100644
> --- a/hw/nvram/eeprom93xx.c
> +++ b/hw/nvram/eeprom93xx.c
> @@ -86,7 +86,7 @@ struct _eeprom_t {
> uint8_t addrbits;
> uint16_t size;
> uint16_t data;
> - uint16_t contents[0];
> + uint16_t contents[];
> };
>
> /* Code for saving and restoring of EEPROM state. */
> diff --git a/hw/rdma/vmw/pvrdma_qp_ops.c b/hw/rdma/vmw/pvrdma_qp_ops.c
> index bd6db858de..8050287a6c 100644
> --- a/hw/rdma/vmw/pvrdma_qp_ops.c
> +++ b/hw/rdma/vmw/pvrdma_qp_ops.c
> @@ -34,13 +34,13 @@ typedef struct CompHandlerCtx {
> /* Send Queue WQE */
> typedef struct PvrdmaSqWqe {
> struct pvrdma_sq_wqe_hdr hdr;
> - struct pvrdma_sge sge[0];
> + struct pvrdma_sge sge[];
> } PvrdmaSqWqe;
>
> /* Recv Queue WQE */
> typedef struct PvrdmaRqWqe {
> struct pvrdma_rq_wqe_hdr hdr;
> - struct pvrdma_sge sge[0];
> + struct pvrdma_sge sge[];
> } PvrdmaRqWqe;
>
> /*
> diff --git a/hw/usb/dev-network.c b/hw/usb/dev-network.c
> index 9a78ad928b..6210427544 100644
> --- a/hw/usb/dev-network.c
> +++ b/hw/usb/dev-network.c
> @@ -626,7 +626,7 @@ static const uint32_t oid_supported_list[] =
> struct rndis_response {
> QTAILQ_ENTRY(rndis_response) entries;
> uint32_t length;
> - uint8_t buf[0];
> + uint8_t buf[];
> };
>
> typedef struct USBNetState {
> diff --git a/hw/usb/dev-smartcard-reader.c b/hw/usb/dev-smartcard-reader.c
> index 02693a26ad..ef72738ced 100644
> --- a/hw/usb/dev-smartcard-reader.c
> +++ b/hw/usb/dev-smartcard-reader.c
> @@ -227,7 +227,7 @@ typedef struct QEMU_PACKED CCID_Parameter {
> typedef struct QEMU_PACKED CCID_DataBlock {
> CCID_BULK_IN b;
> uint8_t bChainParameter;
> - uint8_t abData[0];
> + uint8_t abData[];
> } CCID_DataBlock;
>
> /* 6.1.4 PC_to_RDR_XfrBlock */
> @@ -235,7 +235,7 @@ typedef struct QEMU_PACKED CCID_XferBlock {
> CCID_Header hdr;
> uint8_t bBWI; /* Block Waiting Timeout */
> uint16_t wLevelParameter; /* XXX currently unused */
> - uint8_t abData[0];
> + uint8_t abData[];
> } CCID_XferBlock;
>
> typedef struct QEMU_PACKED CCID_IccPowerOn {
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index b2d415e5dd..b6c8ef5bc0 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -54,7 +54,7 @@ typedef struct VRingAvail
> {
> uint16_t flags;
> uint16_t idx;
> - uint16_t ring[0];
> + uint16_t ring[];
> } VRingAvail;
>
> typedef struct VRingUsedElem
> @@ -67,7 +67,7 @@ typedef struct VRingUsed
> {
> uint16_t flags;
> uint16_t idx;
> - VRingUsedElem ring[0];
> + VRingUsedElem ring[];
> } VRingUsed;
>
> typedef struct VRingMemoryRegionCaches {
> diff --git a/net/queue.c b/net/queue.c
> index 61276ca4be..0164727e39 100644
> --- a/net/queue.c
> +++ b/net/queue.c
> @@ -46,7 +46,7 @@ struct NetPacket {
> unsigned flags;
> int size;
> NetPacketSent *sent_cb;
> - uint8_t data[0];
> + uint8_t data[];
> };
>
> struct NetQueue {
> --
> 2.21.1