sorry, there is a mistake in this patch: the "ret" variable is not
defined :<
I will send a new patch to fix this problem.
On 2015/2/9 12:09, Bin Wu wrote:
> From: Bin Wu <wu.wu...@huawei.com>
>
> The error scenario is as follow: coroutine C1 enters C2, C2 yields
> back to C1, then C1 ternimates and the related coroutine memory
> becomes invalid. After a while, the C2 coroutine is entered again.
> At this point, C1 is used as a parameter passed to
> qemu_co_queue_run_restart. Therefore, qemu_co_queue_run_restart
> accesses an invalid memory and a segfault error ocurrs.
>
> The qemu_co_queue_run_restart function re-enters coroutines waiting
> in the co_queue. However, this function should be only used int the
> qemu_coroutine_enter context. Only in this context, when the current
> coroutine gets execution control again(after the execution of
> qemu_coroutine_switch), we can restart the target coutine because the
> target coutine has yielded back to the current coroutine or it has
> terminated.
>
> First we want to put qemu_co_queue_run_restart in qemu_coroutine_enter,
> but we find we can not access the target coroutine if it terminates.
>
> Signed-off-by: Bin Wu <wu.wu...@huawei.com>
> ---
> qemu-coroutine.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/qemu-coroutine.c b/qemu-coroutine.c
> index 525247b..9a294c4 100644
> --- a/qemu-coroutine.c
> +++ b/qemu-coroutine.c
> @@ -99,24 +99,25 @@ static void coroutine_delete(Coroutine *co)
> qemu_coroutine_delete(co);
> }
>
> -static void coroutine_swap(Coroutine *from, Coroutine *to)
> +static CoroutineAction coroutine_swap(Coroutine *from, Coroutine *to)
> {
> CoroutineAction ret;
>
> ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD);
>
> - qemu_co_queue_run_restart(to);
> -
> switch (ret) {
> case COROUTINE_YIELD:
> - return;
> + break;
> case COROUTINE_TERMINATE:
> trace_qemu_coroutine_terminate(to);
> + qemu_co_queue_run_restart(to);
> coroutine_delete(to);
> - return;
> + break;
> default:
> abort();
> }
> +
> + return ret;
> }
>
> void qemu_coroutine_enter(Coroutine *co, void *opaque)
> @@ -133,6 +134,8 @@ void qemu_coroutine_enter(Coroutine *co, void *opaque)
> co->caller = self;
> co->entry_arg = opaque;
> coroutine_swap(self, co);
> + if (ret == COROUTINE_YIELD)
> + qemu_co_queue_run_restart(co);
> }
>
> void coroutine_fn qemu_coroutine_yield(void)
>
--
Bin Wu
