From 195ed8cb365edeb0d0a70a2ffdeb7a073f9a8117 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 14 Feb 2020 17:17:10 +0000 Subject: [PATCH] qemu/queue.h: add QLIST_SAFE_REMOVE() QLIST_REMOVE() assumes the element is in a list. It also leaves the element's linked list pointers dangling. Introduce a safe version of QLIST_REMOVE() and convert open-coded instances of this pattern. Signed-off-by: Stefan Hajnoczi Reviewed-by: Sergio Lopez Message-id: 20200214171712.541358-4-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- block.c | 5 +---- chardev/spice.c | 4 +--- include/qemu/queue.h | 14 ++++++++++++++ 3 files changed, 16 insertions(+), 7 deletions(-) diff --git a/block.c b/block.c index 308a91c96b..1bdb9c679d 100644 --- a/block.c +++ b/block.c @@ -2636,10 +2636,7 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, static void bdrv_detach_child(BdrvChild *child) { - if (child->next.le_prev) { - QLIST_REMOVE(child, next); - child->next.le_prev = NULL; - } + QLIST_SAFE_REMOVE(child, next); bdrv_replace_child(child, NULL); diff --git a/chardev/spice.c b/chardev/spice.c index 241e2b7770..bf7ea1e294 100644 --- a/chardev/spice.c +++ b/chardev/spice.c @@ -216,9 +216,7 @@ static void char_spice_finalize(Object *obj) vmc_unregister_interface(s); - if (s->next.le_prev) { - QLIST_REMOVE(s, next); - } + QLIST_SAFE_REMOVE(s, next); g_free((char *)s->sin.subtype); g_free((char *)s->sin.portname); diff --git a/include/qemu/queue.h b/include/qemu/queue.h index fcecb70228..60e794a4e3 100644 --- a/include/qemu/queue.h +++ b/include/qemu/queue.h @@ -144,6 +144,20 @@ struct { \ *(elm)->field.le_prev = (elm)->field.le_next; \ } while (/*CONSTCOND*/0) +/* + * Like QLIST_REMOVE() but safe to call when elm is not in a list + */ +#define QLIST_SAFE_REMOVE(elm, field) do { \ + if ((elm)->field.le_prev != NULL) { \ + if ((elm)->field.le_next != NULL) \ + (elm)->field.le_next->field.le_prev = \ + (elm)->field.le_prev; \ + *(elm)->field.le_prev = (elm)->field.le_next; \ + (elm)->field.le_next = NULL; \ + (elm)->field.le_prev = NULL; \ + } \ +} while (/*CONSTCOND*/0) + #define QLIST_FOREACH(var, head, field) \ for ((var) = ((head)->lh_first); \ (var); \ -- 2.39.5