Am Mi., 18. März 2026 um 00:23 Uhr schrieb Peter Xu <[email protected]>: > > We used to have one vmstate called "nullptr" which is only used to generate > one-byte hint to say one pointer is NULL. > > Let's extend its use so that it will generate another byte to say the > pointer is non-NULL. > > With that, the name of the info struct (or functions) do not apply anymore. > Update correspondingly. > > No functional change intended yet. > > Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Alexander Mikhalitsyn <[email protected]> > --- > include/migration/vmstate.h | 9 +++++++-- > migration/vmstate-types.c | 34 ++++++++++++++++------------------ > migration/vmstate.c | 29 ++++++++++++++--------------- > 3 files changed, 37 insertions(+), 35 deletions(-) > > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h > index 092e8f7e9a..2e51b5ea04 100644 > --- a/include/migration/vmstate.h > +++ b/include/migration/vmstate.h > @@ -282,9 +282,14 @@ 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.*/ > +/* > + * Put this in the stream when migrating a pointer to reflect either a NULL > + * or valid pointer. > + */ > #define VMS_MARKER_PTR_NULL (0x30U) /* '0' */ > -extern const VMStateInfo vmstate_info_nullptr; > +#define VMS_MARKER_PTR_VALID (0x31U) /* '1' */ > + > +extern const VMStateInfo vmstate_info_ptr_marker; > > extern const VMStateInfo vmstate_info_cpudouble; > > diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c > index 7622cf8f01..b31689fc3c 100644 > --- a/migration/vmstate-types.c > +++ b/migration/vmstate-types.c > @@ -359,36 +359,34 @@ const VMStateInfo vmstate_info_fd = { > .save = save_fd, > }; > > -static bool load_nullptr(QEMUFile *f, void *pv, size_t size, > - const VMStateField *field, Error **errp) > +static bool load_ptr_marker(QEMUFile *f, void *pv, size_t size, > + const VMStateField *field, Error **errp) > > { > - if (qemu_get_byte(f) == VMS_MARKER_PTR_NULL) { > + int byte = qemu_get_byte(f); > + > + if (byte == VMS_MARKER_PTR_NULL || byte == VMS_MARKER_PTR_VALID) { > + /* TODO: process PTR_VALID case */ > return true; > } > > - error_setg(errp, "vmstate: load_nullptr expected VMS_NULLPTR_MARKER"); > + error_setg(errp, "%s: unexpected ptr marker: %d", __func__, byte); > return false; > } > > -static bool save_nullptr(QEMUFile *f, void *pv, size_t size, > - const VMStateField *field, JSONWriter *vmdesc, > - Error **errp) > +static bool save_ptr_marker(QEMUFile *f, void *pv, size_t size, > + const VMStateField *field, JSONWriter *vmdesc, > + Error **errp) > > { > - if (pv == NULL) { > - qemu_put_byte(f, VMS_MARKER_PTR_NULL); > - return true; > - } > - > - error_setg(errp, "vmstate: save_nullptr must be called with pv == NULL"); > - return false; > + qemu_put_byte(f, pv ? VMS_MARKER_PTR_VALID : VMS_MARKER_PTR_NULL); > + return true; > } > > -const VMStateInfo vmstate_info_nullptr = { > - .name = "nullptr", > - .load = load_nullptr, > - .save = save_nullptr, > +const VMStateInfo vmstate_info_ptr_marker = { > + .name = "ptr-marker", > + .load = load_ptr_marker, > + .save = save_ptr_marker, > }; > > /* 64 bit unsigned int. See that the received value is the same than the one > diff --git a/migration/vmstate.c b/migration/vmstate.c > index 5a6b352764..a3a5f25946 100644 > --- a/migration/vmstate.c > +++ b/migration/vmstate.c > @@ -55,12 +55,12 @@ vmstate_field_exists(const VMStateDescription *vmsd, > const VMStateField *field, > } > > /* > - * Create a fake nullptr field when there's a NULL pointer detected in the > + * Create a ptr marker field when there's a NULL pointer detected in the > * array of a VMS_ARRAY_OF_POINTER VMSD field. It's needed because we > * can't dereference the NULL pointer. > */ > static const VMStateField * > -vmsd_create_fake_nullptr_field(const VMStateField *field) > +vmsd_create_ptr_marker_field(const VMStateField *field) > { > VMStateField *fake = g_new0(VMStateField, 1); > > @@ -76,7 +76,7 @@ vmsd_create_fake_nullptr_field(const VMStateField *field) > > /* See vmstate_info_nullptr - use 1 byte to represent nullptr */ > fake->size = 1; > - fake->info = &vmstate_info_nullptr; > + fake->info = &vmstate_info_ptr_marker; > fake->flags = VMS_SINGLE; > > /* All the rest fields shouldn't matter.. */ > @@ -278,7 +278,7 @@ bool vmstate_load_vmsd(QEMUFile *f, const > VMStateDescription *vmsd, > * an array of pointers), use null placeholder and do > * not follow. > */ > - inner_field = vmsd_create_fake_nullptr_field(field); > + inner_field = vmsd_create_ptr_marker_field(field); > } else { > inner_field = field; > } > @@ -567,7 +567,7 @@ static bool vmstate_save_vmsd_v(QEMUFile *f, const > VMStateDescription *vmsd, > int i, n_elems = vmstate_n_elems(opaque, field); > int size = vmstate_size(opaque, field); > JSONWriter *vmdesc_loop = vmdesc; > - bool is_prev_null = false; > + bool use_marker_field_prev = false; > > trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems); > if (field->flags & VMS_POINTER) { > @@ -578,7 +578,7 @@ static bool vmstate_save_vmsd_v(QEMUFile *f, const > VMStateDescription *vmsd, > for (i = 0; i < n_elems; i++) { > void *curr_elem = first_elem + size * i; > const VMStateField *inner_field; > - bool is_null; > + bool use_marker_field; > int max_elems = n_elems - i; > > if (field->flags & VMS_ARRAY_OF_POINTER) { > @@ -586,17 +586,16 @@ static bool vmstate_save_vmsd_v(QEMUFile *f, const > VMStateDescription *vmsd, > curr_elem = *(void **)curr_elem; > } > > - if (!curr_elem && size) { > + use_marker_field = !curr_elem && size; > + if (use_marker_field) { > /* > * If null pointer found (which should only happen in > * an array of pointers), use null placeholder and do > * not follow. > */ > - inner_field = vmsd_create_fake_nullptr_field(field); > - is_null = true; > + inner_field = vmsd_create_ptr_marker_field(field); > } else { > inner_field = field; > - is_null = false; > } > > /* > @@ -612,16 +611,16 @@ static bool vmstate_save_vmsd_v(QEMUFile *f, const > VMStateDescription *vmsd, > */ > if (vmdesc && vmsd_can_compress(field) && > (field->flags & VMS_ARRAY_OF_POINTER) && > - is_null != is_prev_null) { > + use_marker_field != use_marker_field_prev) { > > - is_prev_null = is_null; > + use_marker_field_prev = use_marker_field; > vmdesc_loop = vmdesc; > > for (int j = i + 1; j < n_elems; j++) { > void *elem = *(void **)(first_elem + size * j); > - bool elem_is_null = !elem && size; > + bool elem_use_marker_field = !elem && size; > > - if (is_null != elem_is_null) { > + if (use_marker_field != elem_use_marker_field) { > max_elems = j - i; > break; > } > @@ -633,7 +632,7 @@ static bool vmstate_save_vmsd_v(QEMUFile *f, const > VMStateDescription *vmsd, > i, max_elems, errp); > > /* If we used a fake temp field.. free it now */ > - if (is_null) { > + if (use_marker_field) { > g_clear_pointer((gpointer *)&inner_field, g_free); > } > > -- > 2.50.1 >
