From: Stefan Hajnoczi <stefanha@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Fam Zheng" <fam@euphon.net>, "Kevin Wolf" <kwolf@redhat.com>,
qemu-block@nongnu.org, "Max Reitz" <mreitz@redhat.com>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Marc-André Lureau" <marcandre.lureau@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>
Subject: [PATCH 3/5] qemu/queue.h: add QLIST_SAFE_REMOVE()
Date: Fri, 14 Feb 2020 17:17:10 +0000 [thread overview]
Message-ID: <20200214171712.541358-4-stefanha@redhat.com> (raw)
In-Reply-To: <20200214171712.541358-1-stefanha@redhat.com>
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 <stefanha@redhat.com>
---
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 9c810534d6..484e01d042 100644
--- a/block.c
+++ b/block.c
@@ -2499,10 +2499,7 @@ 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 19425f973f..a276363372 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); \
--
2.24.1
next prev parent reply other threads:[~2020-02-14 17:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 17:17 [PATCH 0/5] aio-posix: towards an O(1) event loop Stefan Hajnoczi
2020-02-14 17:17 ` [PATCH 1/5] aio-posix: fix use after leaving scope in aio_poll() Stefan Hajnoczi
2020-02-19 7:02 ` Sergio Lopez
2020-02-14 17:17 ` [PATCH 2/5] aio-posix: don't pass ns timeout to epoll_wait() Stefan Hajnoczi
2020-02-19 10:12 ` Sergio Lopez
2020-02-14 17:17 ` Stefan Hajnoczi [this message]
2020-02-19 10:30 ` [PATCH 3/5] qemu/queue.h: add QLIST_SAFE_REMOVE() Sergio Lopez
2020-02-14 17:17 ` [PATCH 4/5] aio-posix: make AioHandler deletion O(1) Stefan Hajnoczi
2020-02-19 10:41 ` Sergio Lopez
2020-02-14 17:17 ` [PATCH 5/5] aio-posix: make AioHandler dispatch O(1) with epoll Stefan Hajnoczi
2020-02-19 11:00 ` Sergio Lopez
2020-02-19 11:13 ` Paolo Bonzini
2020-02-21 12:59 ` Stefan Hajnoczi
2020-02-21 13:06 ` Paolo Bonzini
2020-02-21 14:44 ` Stefan Hajnoczi
2020-02-21 14:47 ` Stefan Hajnoczi
2020-02-21 15:04 ` Paolo Bonzini
2020-02-21 15:29 ` Stefan Hajnoczi
2020-02-21 15:37 ` Paolo Bonzini
2020-02-21 15:29 ` [PATCH 0/5] aio-posix: towards an O(1) event loop Stefan Hajnoczi
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