BusyJay commented on code in PR #2890:
URL: https://github.com/apache/brpc/pull/2890#discussion_r2020463256
##########
src/bthread/task_group.cpp:
##########
@@ -657,7 +715,11 @@ void TaskGroup::sched_to(TaskGroup** pg, TaskMeta*
next_meta) {
g->_control->_task_tracer.set_status(TASK_STATUS_JUMPING,
cur_meta);
g->_control->_task_tracer.set_status(TASK_STATUS_JUMPING,
next_meta);
#endif // BRPC_BTHREAD_TRACER
- jump_stack(cur_meta->stack, next_meta->stack);
+ {
+ BTHREAD_SCOPED_ASAN_FIBER_SWITCHER(
+ cur_meta->stack->storage, cur_ending);
Review Comment:
调用链是：`BTHREAD_SCOPED_ASAN_FIBER_SWITCHER(cur_meta_storage)` ->
`ScopedASanFiberSwitcher(cur_meta_storage)` -> `StartSwitchFiber(&fake_stack,
cur_meta_storage)` -> `BUTIL_ASAN_START_SWITCH_FIBER(&fake_stack,
cur_meta_storage.real_bottom, cur_meta_storage.stacksize)` ->
`__sanitizer_start_switch_fiber(&fake_stack, cur_meta_storage.real_bottom,
cur_meta_storage.stacksize)`.
文档里说后两个参数是要跳转到的栈 meta，所以应该是 next_meta：
> Before switching to a different stack, you must call
<c>__sanitizer_start_switch_fiber()</c> with a pointer to the bottom of the
destination stack and with its size.
> jump_stack之前，需要调__sanitizer_start_switch_fiber()保存fake stack到cur_meta中。
不对，fake_stack 是由 asan 自己根据记录的栈信息进行维护的，并且最终保留在上述 API 传入的第一个参数里。比如从协程 A 跳转协程 B
时调用 start_switch_fiber(&fake_stack_a)，asan 记录的线程栈底和目前的长度会保留在 A 的
`fake_stack_a`。当从别的协程跳回 A 时，A 再调用
finish_switch_fiber(fake_stack_a)，把之前记录的栈底和长度重新恢复到 asan 内部。
fake_stack 不是必须的，可以直接传 nullptr，只要做校验的时候把 detect_stack_use_after_return 设置成 0
即可（gcc13 以前默认就是关闭的）。
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