{"id":2215596,"url":"http://patchwork.ozlabs.org/api/patches/2215596/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260324194333.30004-13-farosas@suse.de/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260324194333.30004-13-farosas@suse.de>","list_archive_url":null,"date":"2026-03-24T19:43:27","name":"[RFC,v1,12/17] vmstate: Introduce vmstate_next","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"836693530976f3e8c456947c0b9855ebc935f8d5","submitter":{"id":85343,"url":"http://patchwork.ozlabs.org/api/people/85343/?format=json","name":"Fabiano Rosas","email":"farosas@suse.de"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260324194333.30004-13-farosas@suse.de/mbox/","series":[{"id":497339,"url":"http://patchwork.ozlabs.org/api/series/497339/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=497339","date":"2026-03-24T19:43:16","name":"migration: vmstate_save|load changes for peterx","version":1,"mbox":"http://patchwork.ozlabs.org/series/497339/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2215596/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2215596/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=suse.de header.i=@suse.de header.a=rsa-sha256\n header.s=susede2_rsa header.b=JNwstzZx;\n\tdkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=xRppBspi;\n\tdkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de\n header.a=rsa-sha256 header.s=susede2_rsa header.b=JNwstzZx;\n\tdkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=xRppBspi;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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t=1774381435;\n h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc:\n mime-version:mime-version:\n content-transfer-encoding:content-transfer-encoding:\n in-reply-to:in-reply-to:references:references;\n bh=x+ZyLFL7XlyGoLVRwdhBcneEFYHFSurRSuZsKKjaQzM=;\n b=xRppBspih78ISK0tY7lDs70KoAoLvDGQbpRljEV+M6ts0WTYtqD84tZur+bSd0uCzIBWIy\n NyQj+rWNm0GHzwBw=="],"From":"Fabiano Rosas ","To":"qemu-devel@nongnu.org","Cc":"Peter Xu ,\n Alexander Mikhalitsyn ,\n Juraj Marcin ","Subject":"[RFC PATCH v1 12/17] vmstate: Introduce vmstate_next","Date":"Tue, 24 Mar 2026 16:43:27 -0300","Message-ID":"<20260324194333.30004-13-farosas@suse.de>","X-Mailer":"git-send-email 2.51.0","In-Reply-To":"<20260324194333.30004-1-farosas@suse.de>","References":"<20260324194333.30004-1-farosas@suse.de>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","X-Spamd-Result":"default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%];\n MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000];\n R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000];\n MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[];\n MIME_TRACE(0.00)[0:+]; FUZZY_RATELIMITED(0.00)[rspamd.com];\n TO_DN_SOME(0.00)[]; ARC_NA(0.00)[];\n DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519];\n URIBL_BLOCKED(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid,suse.de:email];\n FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[];\n RCPT_COUNT_THREE(0.00)[4]; RCVD_COUNT_TWO(0.00)[2];\n TO_MATCH_ENVRCPT_ALL(0.00)[];\n DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,suse.de:email];\n RCVD_TLS_ALL(0.00)[]","X-Spam-Score":"-2.80","Received-SPF":"pass client-ip=195.135.223.131; envelope-from=farosas@suse.de;\n helo=smtp-out2.suse.de","X-Spam_score_int":"-43","X-Spam_score":"-4.4","X-Spam_bar":"----","X-Spam_report":"(-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"Similarly to vmstate_first(), introduce a vmstate_next(), which does\nthe necessary dereferencing of pointers to get to the leaf element. On\nthe load side, allow the caller to pass a flag indicating whether\nallocation is expected and call the allocation function if so.\n\nSigned-off-by: Fabiano Rosas \n---\n migration/vmstate.c | 84 +++++++++++++++++++++------------------------\n 1 file changed, 39 insertions(+), 45 deletions(-)","diff":"diff --git a/migration/vmstate.c b/migration/vmstate.c\nindex ab7c6fa4ab..c1ad0ef9a5 100644\n--- a/migration/vmstate.c\n+++ b/migration/vmstate.c\n@@ -127,24 +127,51 @@ static void *vmstate_first(void *opaque, const VMStateField *field,\n return first;\n }\n \n-static bool vmstate_ptr_marker_load(QEMUFile *f, bool *load_field,\n- Error **errp)\n+static void *vmstate_next(void **first, const VMStateField *field,\n+ int size, int i, bool alloc)\n {\n- int byte = qemu_get_byte(f);\n+ void **array_elem;\n+ void *next;\n+\n+ if (!(field->flags & VMS_ARRAY_OF_POINTER)) {\n+ next = (void *)first + size * i;\n+ return next;\n+ }\n+\n+ array_elem = first + i;\n+ next = *array_elem;\n+\n+ if (alloc) {\n+ if (!next || field->flags & VMS_ARRAY_OF_POINTER_AUTO_ALLOC) {\n+ /*\n+ * NOTE: do not use vmstate_size() here, because we\n+ * need the object size, not entry size of the\n+ * array.\n+ */\n+ next = vmstate_handle_alloc(array_elem, field->size, 1);\n+ }\n+ }\n+ return next;\n+}\n+\n+static bool vmstate_ptr_marker_load(QEMUFile *f, bool *load_field)\n+{\n+ int byte = qemu_peek_byte(f, 0);\n \n if (byte == VMS_MARKER_PTR_NULL) {\n /* When it's a null ptr marker, do not continue the load */\n *load_field = false;\n+ qemu_file_skip(f, 1);\n return true;\n }\n \n if (byte == VMS_MARKER_PTR_VALID) {\n /* We need to load this field right after the marker */\n *load_field = true;\n+ qemu_file_skip(f, 1);\n return true;\n }\n \n- error_setg(errp, \"Unexpected ptr marker: %d\", byte);\n return false;\n }\n \n@@ -273,41 +300,13 @@ bool vmstate_load_vmsd(QEMUFile *f, const VMStateDescription *vmsd,\n void *curr_elem;\n \n if (field->flags & VMS_ARRAY_OF_POINTER) {\n- void **array_elem = (void **)head + i;\n- bool use_dynamic_array =\n- field->flags & VMS_ARRAY_OF_POINTER_AUTO_ALLOC;\n- bool use_marker_field;\n-\n- curr_elem = *array_elem;\n- use_marker_field = use_dynamic_array || !curr_elem;\n-\n- if (use_marker_field) {\n- /* Read the marker instead of VMSD first */\n- if (!vmstate_ptr_marker_load(f, &load_field, errp)) {\n- trace_vmstate_load_field_error(field->name,\n- -EINVAL);\n- return false;\n- }\n-\n- if (load_field) {\n- /*\n- * When reaching here, it means we received a\n- * non-NULL ptr marker, so we need to populate the\n- * field before loading it.\n- *\n- * NOTE: do not use vmstate_size() here, because we\n- * need the object size, not entry size of the\n- * array.\n- */\n- assert(!curr_elem);\n- curr_elem = vmstate_handle_alloc(array_elem,\n- field->size, 1);\n- }\n- }\n- } else {\n- curr_elem = head + size * i;\n+ /* Peek a possible pointer marker instead of VMSD first */\n+ ok = vmstate_ptr_marker_load(f, &load_field);\n }\n \n+ curr_elem = vmstate_next(head, field, size, i,\n+ load_field && ok);\n+\n if (load_field) {\n ok = vmstate_load_field(f, curr_elem, size, field, errp);\n }\n@@ -647,15 +646,11 @@ static bool vmstate_save_vmsd_v(QEMUFile *f, const VMStateDescription *vmsd,\n \n for (i = 0; i < n_elems; i++) {\n bool save_field = true;\n- void *curr_elem;\n+ void *curr_elem = vmstate_next(head, field, size, i, false);\n int max_elems = n_elems - i;\n \n if (field->flags & VMS_ARRAY_OF_POINTER) {\n bool use_marker_field, is_null, use_dynamic_array;\n- void **array_elem = (void **)head + i;\n-\n- assert(array_elem);\n- curr_elem = *array_elem;\n \n is_null = !curr_elem;\n \n@@ -688,7 +683,8 @@ static bool vmstate_save_vmsd_v(QEMUFile *f, const VMStateDescription *vmsd,\n use_vmdesc = true;\n \n for (int j = i + 1; j < n_elems; j++) {\n- void *elem = *(void **)(head + size * j);\n+ void *elem = vmstate_next(head, field, size, j,\n+ false);\n bool elem_is_null = !elem;\n \n if (is_null != elem_is_null) {\n@@ -713,8 +709,6 @@ static bool vmstate_save_vmsd_v(QEMUFile *f, const VMStateDescription *vmsd,\n \n save_field = !!curr_elem;\n }\n- } else {\n- curr_elem = head + size * i;\n }\n \n if (save_field) {\n","prefixes":["RFC","v1","12/17"]}