On 10/14/2016 10:04 AM, Dr. David Alan Gilbert wrote: > * Jianjun Duan (du...@linux.vnet.ibm.com) wrote: >> >> >> On 10/14/2016 03:44 AM, Dr. David Alan Gilbert wrote: >>> * Jianjun Duan (du...@linux.vnet.ibm.com) wrote: >>>> Currently we cannot directly transfer a QTAILQ instance because of the >>>> limitation in the migration code. Here we introduce an approach to >>>> transfer such structures. We created VMStateInfo vmstate_info_qtailq >>>> for QTAILQ. Similar VMStateInfo can be created for other data structures >>>> such as list. >>>> >>>> This approach will be used to transfer pending_events and ccs_list in spapr >>>> state. >>>> >>>> We also create some macros in qemu/queue.h to access a QTAILQ using pointer >>>> arithmetic. This ensures that we do not depend on the implementation >>>> details about QTAILQ in the migration code. >>>> >>>> Signed-off-by: Jianjun Duan <du...@linux.vnet.ibm.com> >>>> --- >>>> include/migration/vmstate.h | 20 +++++++++++++++ >>>> include/qemu/queue.h | 32 ++++++++++++++++++++++++ >>>> migration/trace-events | 4 +++ >>>> migration/vmstate.c | 59 >>>> +++++++++++++++++++++++++++++++++++++++++++++ >>>> 4 files changed, 115 insertions(+) >>>> >>>> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h >>>> index d0e37b5..4dd0aed 100644 >>>> --- a/include/migration/vmstate.h >>>> +++ b/include/migration/vmstate.h >>>> @@ -251,6 +251,7 @@ extern const VMStateInfo vmstate_info_timer; >>>> extern const VMStateInfo vmstate_info_buffer; >>>> extern const VMStateInfo vmstate_info_unused_buffer; >>>> extern const VMStateInfo vmstate_info_bitmap; >>>> +extern const VMStateInfo vmstate_info_qtailq; >>>> >>>> #define type_check_2darray(t1,t2,n,m) ((t1(*)[n][m])0 - (t2*)0) >>>> #define type_check_array(t1,t2,n) ((t1(*)[n])0 - (t2*)0) >>>> @@ -662,6 +663,25 @@ extern const VMStateInfo vmstate_info_bitmap; >>>> .offset = offsetof(_state, _field), \ >>>> } >>>> >>>> +/* For QTAILQ that need customized handling >>>> + * _type: type of QTAILQ element >>>> + * _next: name of QTAILQ entry field in QTAILQ element >>>> + * _vmsd: VMSD for QTAILQ element >>>> + * size: size of QTAILQ element >>>> + * start: offset of QTAILQ entry in QTAILQ element >>>> + */ >>>> +#define VMSTATE_QTAILQ_V(_field, _state, _version, _vmsd, _type, _next) \ >>>> +{ \ >>>> + .name = (stringify(_field)), \ >>>> + .version_id = (_version), \ >>>> + .vmsd = &(_vmsd), \ >>>> + .size = sizeof(_type), \ >>>> + .info = &vmstate_info_qtailq, \ >>>> + .flags = VMS_LINKED, \ >>> >>> Hang on - you killed VMS_LINKED off in the previous patch; so this >>> doesn't work. >>> (Adding a test to tests/test-vmstate.c would have found that) >>> >> >> Thanks for pointing it out. Since the actual application of this patch >> is split off, my test didn't go through this path. > > Yes, but you could add a new entry into test-vmstate.c for this.
OK. > >>>> + .offset = offsetof(_state, _field), \ >>>> + .start = offsetof(_type, _next), \ >>>> +} >>>> + >>>> /* _f : field name >>>> _f_n : num of elements field_name >>>> _n : num of elements >>>> diff --git a/include/qemu/queue.h b/include/qemu/queue.h >>>> index 342073f..d672ae0 100644 >>>> --- a/include/qemu/queue.h >>>> +++ b/include/qemu/queue.h >>>> @@ -438,4 +438,36 @@ struct { >>>> \ >>>> #define QTAILQ_PREV(elm, headname, field) \ >>>> (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) >>>> >>>> +/* >>>> + * Offsets of layout of a tail queue head. >>>> + */ >>>> +#define QTAILQ_FIRST_OFFSET 0 >>>> +#define QTAILQ_LAST_OFFSET (sizeof(void *)) >>>> + >>>> +/* >>>> + * Offsets of layout of a tail queue element. >>>> + */ >>>> +#define QTAILQ_NEXT_OFFSET 0 >>>> +#define QTAILQ_PREV_OFFSET (sizeof(void *)) >>>> + >>>> +/* >>>> + * Tail queue tranversal using pointer arithmetic. >>>> + */ >>>> +#define QTAILQ_RAW_FOREACH(elm, head, entry) >>>> \ >>>> + for ((elm) = *((void **) ((char *) (head) + >>>> QTAILQ_FIRST_OFFSET)); \ >>>> + (elm); >>>> \ >>>> + (elm) = >>>> \ >>>> + *((void **) ((char *) (elm) + (entry) + >>>> QTAILQ_NEXT_OFFSET))) >>>> +/* >>>> + * Tail queue insertion using pointer arithmetic. >>>> + */ >>>> +#define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do { >>>> \ >>>> + *((void **) ((char *) (elm) + (entry) + QTAILQ_NEXT_OFFSET)) = >>>> NULL; \ >>>> + *((void **) ((char *) (elm) + (entry) + QTAILQ_PREV_OFFSET)) = >>>> \ >>>> + *((void **) ((char *) (head) + QTAILQ_LAST_OFFSET)); >>>> \ >>>> + **((void ***)((char *) (head) + QTAILQ_LAST_OFFSET)) = (elm); >>>> \ >>>> + *((void **) ((char *) (head) + QTAILQ_LAST_OFFSET)) = >>>> \ >>>> + (void *) ((char *) (elm) + (entry) + QTAILQ_NEXT_OFFSET); >>>> \ >>>> +} while (/*CONSTCOND*/0) >>> >>> I wonder if there's a simpler way to do this; I'm not sure this works, but >>> something like: >>> >>> struct QTAILQDummy { >>> char dummy; >>> }; >>> >>> QTAILQ_HEAD(QTAILQRawHead, struct QTAILQDummy) >>> typedef QTAILQ_ENTRY(struct QTAILQDummy) QTAILQRawEntry; >>> >>> #define QTAILQ_RAW_FOREACH(elm, head, entry) >>> \ >>> for ((elm) = ((struct QTAILQRawHead *)head)->tqh_first) >>> \ >>> (elm); >>> \ >>> (elm) = >>> \ >>> (elm) = ((QTAILQRawEntry *)((char *) (elm) + >>> (entry)))->tqh_next >>> >>> and then I think elm gets declared as a struct QTAILQDummy. >>> But it does avoid those FIRST_OFFSET/LAST_OFFSET/NEXT_OFFSET/PREV_OFFSET >>> calculations. >>> >>> Would that work? >>> >> It is intended for QTAILQ of any type. So type is not available. > > I think it might be possible to do it generally. > If we have type, then we can use what is there already, and don't need a pointer arithmetic based approach. Inside put/get, we only get type layout info from vmsd, which is all about size and offset. This macro is used inside put/get, so I am not sure how we can directly use type here. >>>> #endif /* QEMU_SYS_QUEUE_H */ >>>> diff --git a/migration/trace-events b/migration/trace-events >>>> index dfee75a..9a6ec59 100644 >>>> --- a/migration/trace-events >>>> +++ b/migration/trace-events >>>> @@ -52,6 +52,10 @@ vmstate_n_elems(const char *name, int n_elems) "%s: %d" >>>> vmstate_subsection_load(const char *parent) "%s" >>>> vmstate_subsection_load_bad(const char *parent, const char *sub, const >>>> char *sub2) "%s: %s/%s" >>>> vmstate_subsection_load_good(const char *parent) "%s" >>>> +get_qtailq(const char *name, int version_id) "%s v%d" >>>> +get_qtailq_end(const char *name, const char *reason, int val) "%s %s/%d" >>>> +put_qtailq(const char *name, int version_id) "%s v%d" >>>> +put_qtailq_end(const char *name, const char *reason) "%s %s" >>>> >>>> # migration/qemu-file.c >>>> qemu_file_fclose(void) "" >>>> diff --git a/migration/vmstate.c b/migration/vmstate.c >>>> index e8eff3f..eb68fc6 100644 >>>> --- a/migration/vmstate.c >>>> +++ b/migration/vmstate.c >>>> @@ -5,6 +5,7 @@ >>>> #include "migration/vmstate.h" >>>> #include "qemu/bitops.h" >>>> #include "qemu/error-report.h" >>>> +#include "qemu/queue.h" >>>> #include "trace.h" >>>> #include "migration/qjson.h" >>>> >>>> @@ -946,3 +947,61 @@ const VMStateInfo vmstate_info_bitmap = { >>>> .get = get_bitmap, >>>> .put = put_bitmap, >>>> }; >>>> + >>>> +/*get for QTAILQ */ >>>> +static int get_qtailq(QEMUFile *f, void *pv, size_t unused_size, >>>> + VMStateField *field) >>>> +{ >>>> + int ret = 0; >>>> + const VMStateDescription *vmsd = field->vmsd; >>>> + size_t size = field->size; >>>> + size_t entry = field->start; >>> >>> Please comment these two here; I'd prefer entry_offset or something >>> as a name to make clear what it is. >>> >> OK. >>>> + int version_id = field->version_id; >>>> + void *elm; >>>> + >>>> + trace_get_qtailq(vmsd->name, version_id); >>>> + if (version_id > vmsd->version_id) { >>>> + trace_get_qtailq_end(vmsd->name, "too new", -EINVAL); >>>> + return -EINVAL; >>>> + } >>>> + if (version_id < vmsd->minimum_version_id) { >>>> + trace_get_qtailq_end(vmsd->name, "too old", -EINVAL); >>>> + return -EINVAL; >>>> + } >>> >>> Please make those error_report's - if anything fails migration >>> I like to see it in the stderr log. >>> >> I know previously you wanted it to be error report. But in the migration >> code the same error is always just put into trace (vmastate_load_state). >> I just want to be consistent. > > I should fix those as well to add error_reports ! > It's very difficult when we get an error back from a customer with just > a migration failure when the only thing we know is an -EINVAL, so I keep > adding error_report calls. > OK. I will add err reports in vmstate.c. Thanks, Jianjun > Dave > >> Thanks, >> Jianjun >>>> + while (qemu_get_byte(f)) { >>>> + elm = g_malloc(size); >>>> + ret = vmstate_load_state(f, vmsd, elm, version_id); >>>> + if (ret) { >>>> + return ret; >>>> + } >>>> + QTAILQ_RAW_INSERT_TAIL(pv, elm, entry); >>>> + } >>>> + >>>> + trace_get_qtailq_end(vmsd->name, "end", ret); >>>> + return ret; >>>> +} >>>> + >>>> +/* put for QTAILQ */ >>>> +static void put_qtailq(QEMUFile *f, void *pv, size_t unused_size, >>>> + VMStateField *field, QJSON *vmdesc) >>>> +{ >>>> + const VMStateDescription *vmsd = field->vmsd; >>>> + size_t entry = field->start; >>>> + void *elm; >>>> + >>>> + trace_put_qtailq(vmsd->name, vmsd->version_id); >>>> + >>>> + QTAILQ_RAW_FOREACH(elm, pv, entry) { >>>> + qemu_put_byte(f, true); >>>> + vmstate_save_state(f, vmsd, elm, vmdesc); >>>> + } >>>> + qemu_put_byte(f, false); >>>> + >>>> + trace_put_qtailq_end(vmsd->name, "end"); >>>> +} >>>> +const VMStateInfo vmstate_info_qtailq = { >>>> + .name = "qtailq", >>>> + .get = get_qtailq, >>>> + .put = put_qtailq, >>>> +}; >>>> -- >>>> 1.9.1 >>> >>> Dave >>> >>>> >>> -- >>> Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK >>> >> > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK >