From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34192) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c0CUl-0002yp-AS for qemu-devel@nongnu.org; Fri, 28 Oct 2016 15:07:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c0CUg-0002ef-9a for qemu-devel@nongnu.org; Fri, 28 Oct 2016 15:07:15 -0400 Date: Fri, 28 Oct 2016 20:06:58 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20161028190657.GB2173@work-vm> References: <1477607317-27817-1-git-send-email-duanj@linux.vnet.ibm.com> <1477607317-27817-3-git-send-email-duanj@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1477607317-27817-3-git-send-email-duanj@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [QEMU PATCH v9 2/3] migration: migrate QTAILQ List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jianjun Duan Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, dmitry@daynix.com, peter.maydell@linaro.org, kraxel@redhat.com, mst@redhat.com, david@gibson.dropbear.id.au, pbonzini@redhat.com, veroniabahaa@gmail.com, quintela@redhat.com, amit.shah@redhat.com, mreitz@redhat.com, kwolf@redhat.com, rth@twiddle.net, aurelien@aurel32.net, leon.alrae@imgtec.com, blauwirbel@gmail.com, mark.cave-ayland@ilande.co.uk, mdroth@linux.vnet.ibm.com * Jianjun Duan (duanj@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 > --- > include/migration/vmstate.h | 20 ++++++++++++++ > include/qemu/queue.h | 61 +++++++++++++++++++++++++++++++++++++++++ > migration/trace-events | 4 +++ > migration/vmstate.c | 67 +++++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 152 insertions(+) > > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h > index d0e37b5..318a6f1 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. > + * Target QTAILQ needs be properly initialized. > + * _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, \ > + .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..16af127 100644 > --- a/include/qemu/queue.h > +++ b/include/qemu/queue.h > @@ -438,4 +438,65 @@ struct { \ > #define QTAILQ_PREV(elm, headname, field) \ > (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) > > +#define field_at_offset(base, offset, type) \ > + ((type) (((char *) (base)) + (offset))) > + > +typedef struct DUMB_Q_ENTRY DUMB_Q_ENTRY; > +typedef struct DUMB_Q DUMB_Q; > + > +struct DUMB_Q_ENTRY { > + QTAILQ_ENTRY(DUMB_Q_ENTRY) next; > +}; > + > +struct DUMB_Q { > + QTAILQ_HEAD(DUMB_Q_HEAD, DUMB_Q_ENTRY) head; > +}; OK, good we've got rid of the hard coded offsets; thanks! > +#define dumb_q ((DUMB_Q *) 0) > +#define dumb_qh ((typeof(dumb_q->head) *) 0) > +#define dumb_qe ((DUMB_Q_ENTRY *) 0) Note that 'dumb' and 'dummy' are completely different words; this is a dummy not a dumb. > +/* > + * Offsets of layout of a tail queue head. > + */ > +#define QTAILQ_FIRST_OFFSET ((size_t) &(QTAILQ_FIRST(dumb_qh))) Isn't that just offsetof(dumb_qh, tqh_first) ? > +#define QTAILQ_LAST_OFFSET (offsetof(typeof(dumb_q->head), tqh_last)) Similarly isnt't that just offsetof(DUMB_Q_HEAD, tqh_last) ? > +/* > + * Raw access of elements of a tail queue > + */ > +#define QTAILQ_RAW_FIRST(head) \ > + (*field_at_offset(head, QTAILQ_FIRST_OFFSET, void **)) > +#define QTAILQ_RAW_LAST(head) \ > + (*field_at_offset(head, QTAILQ_LAST_OFFSET, void ***)) > + > +/* > + * Offsets of layout of a tail queue element. > + */ > +#define QTAILQ_NEXT_OFFSET ((size_t) (&QTAILQ_NEXT(dumb_qe, next))) > +#define QTAILQ_PREV_OFFSET (offsetof(typeof(dumb_qe->next), tqe_prev)) Similar comments to the pair above. Dave P.S. I'm out next week, so please someone else jump in. > +/* > + * Raw access of elements of a tail entry > + */ > +#define QTAILQ_RAW_NEXT(elm, entry) \ > + (*field_at_offset(elm, entry + QTAILQ_NEXT_OFFSET, void **)) > +#define QTAILQ_RAW_PREV(elm, entry) \ > + (*field_at_offset(elm, entry + QTAILQ_PREV_OFFSET, void ***)) > +/* > + * Tail queue tranversal using pointer arithmetic. > + */ > +#define QTAILQ_RAW_FOREACH(elm, head, entry) \ > + for ((elm) = QTAILQ_RAW_FIRST(head); \ > + (elm); \ > + (elm) = QTAILQ_RAW_NEXT(elm, entry)) > +/* > + * Tail queue insertion using pointer arithmetic. > + */ > +#define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do { \ > + QTAILQ_RAW_NEXT(elm, entry) = NULL; \ > + QTAILQ_RAW_PREV(elm, entry) = QTAILQ_RAW_LAST(head); \ > + *QTAILQ_RAW_LAST(head) = (elm); \ > + QTAILQ_RAW_LAST(head) = &QTAILQ_RAW_NEXT(elm, entry); \ > +} while (/*CONSTCOND*/0) > + > #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 d188afa..70e0472 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" > > @@ -948,3 +949,69 @@ const VMStateInfo vmstate_info_bitmap = { > .get = get_bitmap, > .put = put_bitmap, > }; > + > +/* get for QTAILQ > + * meta data about the QTAILQ is encoded in a VMStateField structure > + */ > +static int get_qtailq(QEMUFile *f, void *pv, size_t unused_size, > + VMStateField *field) > +{ > + int ret = 0; > + const VMStateDescription *vmsd = field->vmsd; > + /* size of a QTAILQ element */ > + size_t size = field->size; > + /* offset of the QTAILQ entry in a QTAILQ element */ > + size_t entry_offset = field->start; > + int version_id = field->version_id; > + void *elm; > + > + trace_get_qtailq(vmsd->name, version_id); > + if (version_id > vmsd->version_id) { > + error_report("%s %s", vmsd->name, "too new"); > + trace_get_qtailq_end(vmsd->name, "too new", -EINVAL); > + > + return -EINVAL; > + } > + if (version_id < vmsd->minimum_version_id) { > + error_report("%s %s", vmsd->name, "too old"); > + trace_get_qtailq_end(vmsd->name, "too old", -EINVAL); > + return -EINVAL; > + } > + > + 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_offset); > + } > + > + 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; > + /* offset of the QTAILQ entry in a QTAILQ element*/ > + size_t entry_offset = field->start; > + void *elm; > + > + trace_put_qtailq(vmsd->name, vmsd->version_id); > + > + QTAILQ_RAW_FOREACH(elm, pv, entry_offset) { > + 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 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK