On Mon, Sep 30, 2024 at 12:40:39PM -0700, Steve Sistare wrote:
> Define VMSTATE_FD for declaring a file descriptor field in a
> VMStateDescription.
>
> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
> ---
> include/migration/vmstate.h | 9 +++++++++
> migration/vmstate-types.c | 32 ++++++++++++++++++++++++++++++++
> 2 files changed, 41 insertions(+)
>
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index f313f2f..a1dfab4 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -230,6 +230,7 @@ extern const VMStateInfo vmstate_info_uint8;
> extern const VMStateInfo vmstate_info_uint16;
> extern const VMStateInfo vmstate_info_uint32;
> extern const VMStateInfo vmstate_info_uint64;
> +extern const VMStateInfo vmstate_info_fd;
>
> /** Put this in the stream when migrating a null pointer.*/
> #define VMS_NULLPTR_MARKER (0x30U) /* '0' */
> @@ -902,6 +903,9 @@ extern const VMStateInfo vmstate_info_qlist;
> #define VMSTATE_UINT64_V(_f, _s, _v) \
> VMSTATE_SINGLE(_f, _s, _v, vmstate_info_uint64, uint64_t)
>
> +#define VMSTATE_FD_V(_f, _s, _v) \
> + VMSTATE_SINGLE(_f, _s, _v, vmstate_info_fd, int32_t)
> +
> #ifdef CONFIG_LINUX
>
> #define VMSTATE_U8_V(_f, _s, _v) \
> @@ -936,6 +940,9 @@ extern const VMStateInfo vmstate_info_qlist;
> #define VMSTATE_UINT64(_f, _s) \
> VMSTATE_UINT64_V(_f, _s, 0)
>
> +#define VMSTATE_FD(_f, _s) \
> + VMSTATE_FD_V(_f, _s, 0)
> +
> #ifdef CONFIG_LINUX
>
> #define VMSTATE_U8(_f, _s) \
> @@ -1009,6 +1016,8 @@ extern const VMStateInfo vmstate_info_qlist;
> #define VMSTATE_UINT64_TEST(_f, _s, _t) \
> VMSTATE_SINGLE_TEST(_f, _s, _t, 0, vmstate_info_uint64, uint64_t)
>
> +#define VMSTATE_FD_TEST(_f, _s, _t)
> \
> + VMSTATE_SINGLE_TEST(_f, _s, _t, 0, vmstate_info_fd, int32_t)
>
> #define VMSTATE_TIMER_PTR_TEST(_f, _s, _test) \
> VMSTATE_POINTER_TEST(_f, _s, _test, vmstate_info_timer, QEMUTimer *)
> diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c
> index e83bfcc..6e45a4a 100644
> --- a/migration/vmstate-types.c
> +++ b/migration/vmstate-types.c
> @@ -314,6 +314,38 @@ const VMStateInfo vmstate_info_uint64 = {
> .put = put_uint64,
> };
>
> +/* File descriptor communicated via SCM_RIGHTS */
> +
> +static int get_fd(QEMUFile *f, void *pv, size_t size,
> + const VMStateField *field)
> +{
> + int32_t *v = pv;
> + qemu_get_sbe32s(f, v);
Why we need to send/recv the fd integer alone? Can't that change anyway
across migration? What happens if we drop this (and the put side)?
> + if (*v < 0) {
> + return 0;
> + }
> + *v = qemu_file_get_fd(f);
> + return 0;
> +}
> +
> +static int put_fd(QEMUFile *f, void *pv, size_t size,
> + const VMStateField *field, JSONWriter *vmdesc)
> +{
> + int32_t *v = pv;
> +
> + qemu_put_sbe32s(f, v);
> + if (*v < 0) {
> + return 0;
> + }
> + return qemu_file_put_fd(f, *v);
> +}
> +
> +const VMStateInfo vmstate_info_fd = {
> + .name = "fd",
> + .get = get_fd,
> + .put = put_fd,
> +};
> +
> static int get_nullptr(QEMUFile *f, void *pv, size_t size,
> const VMStateField *field)
>
> --
> 1.8.3.1
>
--
Peter Xu
