To fix potential deadlocks as reported by tsan.
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>
Signed-off-by: Emilio Cota <c...@braap.org>
---
plugins/core.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/plugins/core.c b/plugins/core.c
index ccb770a485..728bacef95 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -500,10 +500,17 @@ void qemu_plugin_user_exit(void)
enum qemu_plugin_event ev;
CPUState *cpu;
- QEMU_LOCK_GUARD(&plugin.lock);
-
+ /*
+ * Locking order: we must acquire locks in an order that is consistent
+ * with the one in fork_start(). That is:
+ * - start_exclusive(), which acquires qemu_cpu_list_lock,
+ * must be called before acquiring plugin.lock.
+ * - tb_flush(), which acquires mmap_lock(), must be called
+ * while plugin.lock is not held.
+ */
start_exclusive();
+ qemu_rec_mutex_lock(&plugin.lock);
/* un-register all callbacks except the final AT_EXIT one */
for (ev = 0; ev < QEMU_PLUGIN_EV_MAX; ev++) {
if (ev != QEMU_PLUGIN_EV_ATEXIT) {
@@ -513,13 +520,12 @@ void qemu_plugin_user_exit(void)
}
}
}
-
- tb_flush(current_cpu);
-
CPU_FOREACH(cpu) {
qemu_plugin_disable_mem_helpers(cpu);
}
+ qemu_rec_mutex_unlock(&plugin.lock);
+ tb_flush(current_cpu);
end_exclusive();
/* now it's safe to handle the exit case */
--
2.34.1
