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[Qemu-devel] [PATCH 2/8] exec: don't use cpu_index to detect if cpu_exec
From: |
Igor Mammedov |
Subject: |
[Qemu-devel] [PATCH 2/8] exec: don't use cpu_index to detect if cpu_exec_init()'s been called for cpu |
Date: |
Thu, 21 Jul 2016 17:54:33 +0200 |
Instead use QTAIL's tqe_prev field to detect if cpu's been
placed in list by cpu_exec_init() which is always set if
QTAIL element is in list.
Fixes SIGSEGV on failure path in case cpu_index is assigned
by board and cpu.relalize() fails before cpu_exec_init() is called.
In follow up patches, cpu_index will be assigned by boards that
support cpu hot(un)plug and need stable cpu_index that doesn't
depend on order cpus are created/removed.
Signed-off-by: Igor Mammedov <address@hidden>
Reported-by: David Gibson <address@hidden>
---
include/qemu/queue.h | 2 ++
exec.c | 4 ++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/qemu/queue.h b/include/qemu/queue.h
index c2b6c81..2c2c74b 100644
--- a/include/qemu/queue.h
+++ b/include/qemu/queue.h
@@ -407,6 +407,7 @@ struct {
\
else \
(head)->tqh_last = (elm)->field.tqe_prev; \
*(elm)->field.tqe_prev = (elm)->field.tqe_next; \
+ (elm)->field.tqe_prev = NULL; \
} while (/*CONSTCOND*/0)
#define QTAILQ_FOREACH(var, head, field) \
@@ -430,6 +431,7 @@ struct {
\
#define QTAILQ_EMPTY(head) ((head)->tqh_first == NULL)
#define QTAILQ_FIRST(head) ((head)->tqh_first)
#define QTAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
+#define QTAILQ_IN_USE(elm, field) ((elm)->field.tqe_prev)
#define QTAILQ_LAST(head, headname) \
(*(((struct headname *)((head)->tqh_last))->tqh_last))
diff --git a/exec.c b/exec.c
index 2f57c62..8c5da32 100644
--- a/exec.c
+++ b/exec.c
@@ -643,8 +643,8 @@ void cpu_exec_exit(CPUState *cpu)
CPUClass *cc = CPU_GET_CLASS(cpu);
cpu_list_lock();
- if (cpu->cpu_index == -1) {
- /* cpu_index was never allocated by this @cpu or was already freed. */
+ if (!QTAILQ_IN_USE(cpu, node)) {
+ /* there is nothing to undo since cpu_exec_init() hasn't been called */
cpu_list_unlock();
return;
}
--
2.7.4
- [Qemu-devel] [PATCH 0/8] Fix migration issues with arbitrary cpu-hot(un)plug, Igor Mammedov, 2016/07/21
- [Qemu-devel] [PATCH 2/8] exec: don't use cpu_index to detect if cpu_exec_init()'s been called for cpu,
Igor Mammedov <=
- [Qemu-devel] [PATCH 1/8] exec: reduce CONFIG_USER_ONLY ifdeffenery, Igor Mammedov, 2016/07/21
- [Qemu-devel] [PATCH 3/8] exec: set cpu_index only if it's been explictly set, Igor Mammedov, 2016/07/21
- [Qemu-devel] [PATCH 5/8] pc: init CPUState->cpu_index with index in possible_cpus[], Igor Mammedov, 2016/07/21
- [Qemu-devel] [PATCH 4/8] qdev: fix object reference leak in case device.realize() fails, Igor Mammedov, 2016/07/21