From c5f9e92cd49a2171a5b0223cafd7fab3f45edb82 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Tue, 9 Jan 2024 19:17:17 +0100 Subject: [PATCH 06/22] string-output-visitor: Fix (pseudo) struct handling RH-Author: Stefan Hajnoczi RH-MergeRequest: 219: virtio-blk: add iothread-vq-mapping parameter RH-Jira: RHEL-17369 RHEL-20764 RHEL-7356 RH-Acked-by: Kevin Wolf RH-Acked-by: Hanna Czenczek RH-Commit: [2/17] 84e226f161680dd61b6635e213203d062c1aa556 (stefanha/centos-stream-qemu-kvm) Commit ff32bb53 tried to get minimal struct support into the string output visitor by just making it return "". Unfortunately, it forgot that the caller will still make more visitor calls for the content of the struct. If the struct is contained in a list, such as IOThreadVirtQueueMapping, in the better case its fields show up as separate list entries. In the worse case, it contains another list, and the string output visitor doesn't support nested lists and asserts that this doesn't happen. So as soon as the optional "vqs" field in IOThreadVirtQueueMapping is specified, we get a crash. This can be reproduced with the following command line: echo "info qtree" | ./qemu-system-x86_64 \ -object iothread,id=t0 \ -blockdev null-co,node-name=disk \ -device '{"driver": "virtio-blk-pci", "drive": "disk", "iothread-vq-mapping": [{"iothread": "t0", "vqs": [0]}]}' \ -monitor stdio Fix the problem by counting the nesting level of structs and ignoring any visitor calls for values (apart from start/end_struct) while we're not on the top level. Lists nested directly within lists remain unimplemented, as we don't currently have a use case for them. Fixes: ff32bb53476539d352653f4ed56372dced73a388 Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2069 Reported-by: Aihua Liang Signed-off-by: Kevin Wolf Message-ID: <20240109181717.42493-1-kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf (cherry picked from commit 014b99a8e41c8cd1e895137654b44dec5430122c) Signed-off-by: Stefan Hajnoczi --- qapi/string-output-visitor.c | 46 ++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c index f0c1dea89e..5115536b15 100644 --- a/qapi/string-output-visitor.c +++ b/qapi/string-output-visitor.c @@ -65,6 +65,7 @@ struct StringOutputVisitor } range_start, range_end; GList *ranges; void *list; /* Only needed for sanity checking the caller */ + unsigned int struct_nesting; }; static StringOutputVisitor *to_sov(Visitor *v) @@ -144,6 +145,10 @@ static bool print_type_int64(Visitor *v, const char *name, int64_t *obj, StringOutputVisitor *sov = to_sov(v); GList *l; + if (sov->struct_nesting) { + return true; + } + switch (sov->list_mode) { case LM_NONE: string_output_append(sov, *obj); @@ -231,6 +236,10 @@ static bool print_type_size(Visitor *v, const char *name, uint64_t *obj, uint64_t val; char *out, *psize; + if (sov->struct_nesting) { + return true; + } + if (!sov->human) { out = g_strdup_printf("%"PRIu64, *obj); string_output_set(sov, out); @@ -250,6 +259,11 @@ static bool print_type_bool(Visitor *v, const char *name, bool *obj, Error **errp) { StringOutputVisitor *sov = to_sov(v); + + if (sov->struct_nesting) { + return true; + } + string_output_set(sov, g_strdup(*obj ? "true" : "false")); return true; } @@ -260,6 +274,10 @@ static bool print_type_str(Visitor *v, const char *name, char **obj, StringOutputVisitor *sov = to_sov(v); char *out; + if (sov->struct_nesting) { + return true; + } + if (sov->human) { out = *obj ? g_strdup_printf("\"%s\"", *obj) : g_strdup(""); } else { @@ -273,6 +291,11 @@ static bool print_type_number(Visitor *v, const char *name, double *obj, Error **errp) { StringOutputVisitor *sov = to_sov(v); + + if (sov->struct_nesting) { + return true; + } + string_output_set(sov, g_strdup_printf("%.17g", *obj)); return true; } @@ -283,6 +306,10 @@ static bool print_type_null(Visitor *v, const char *name, QNull **obj, StringOutputVisitor *sov = to_sov(v); char *out; + if (sov->struct_nesting) { + return true; + } + if (sov->human) { out = g_strdup(""); } else { @@ -295,6 +322,9 @@ static bool print_type_null(Visitor *v, const char *name, QNull **obj, static bool start_struct(Visitor *v, const char *name, void **obj, size_t size, Error **errp) { + StringOutputVisitor *sov = to_sov(v); + + sov->struct_nesting++; return true; } @@ -302,6 +332,10 @@ static void end_struct(Visitor *v, void **obj) { StringOutputVisitor *sov = to_sov(v); + if (--sov->struct_nesting) { + return; + } + /* TODO actually print struct fields */ string_output_set(sov, g_strdup("")); } @@ -312,6 +346,10 @@ start_list(Visitor *v, const char *name, GenericList **list, size_t size, { StringOutputVisitor *sov = to_sov(v); + if (sov->struct_nesting) { + return true; + } + /* we can't traverse a list in a list */ assert(sov->list_mode == LM_NONE); /* We don't support visits without a list */ @@ -329,6 +367,10 @@ static GenericList *next_list(Visitor *v, GenericList *tail, size_t size) StringOutputVisitor *sov = to_sov(v); GenericList *ret = tail->next; + if (sov->struct_nesting) { + return ret; + } + if (ret && !ret->next) { sov->list_mode = LM_END; } @@ -339,6 +381,10 @@ static void end_list(Visitor *v, void **obj) { StringOutputVisitor *sov = to_sov(v); + if (sov->struct_nesting) { + return; + } + assert(sov->list == obj); assert(sov->list_mode == LM_STARTED || sov->list_mode == LM_END || -- 2.39.3