Re: [Qemu-devel] [PATCH 1/3] colo-compare: serialize compare thread's initialization with main thread

[Hailiang Zhang <zhang.zhanghailiang@huawei.com>]

On 2017/4/24 12:10, Jason Wang wrote:
>
> On 2017年04月20日 15:46, zhanghailiang wrote:
>> We call qemu_chr_fe_set_handlers() in colo-compare thread, it is used
>> to detach watched fd from default main context, so it has chance to
>> handle the same watched fd with main thread concurrently, which will
>> trigger an error report:
>> "qemu-char.c:918: io_watch_poll_finalize: Assertion `iwp->src == ((void *)0)' failed."
> Anyway to prevent fd from being handled by main thread before creating
> colo thread? Using semaphore seems not elegant.

So how about calling qemu_mutex_lock_iothread() before qemu_chr_fe_set_handlers() ?

> Thanks
>
>> Fix it by serializing compare thread's initialization with main thread.
>>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> ---
>>    net/colo-compare.c | 6 ++++++
>>    1 file changed, 6 insertions(+)
>>
>> diff --git a/net/colo-compare.c b/net/colo-compare.c
>> index 54e6d40..a6bf419 100644
>> --- a/net/colo-compare.c
>> +++ b/net/colo-compare.c
>> @@ -83,6 +83,7 @@ typedef struct CompareState {
>>        GHashTable *connection_track_table;
>>        /* compare thread, a thread for each NIC */
>>        QemuThread thread;
>> +    QemuSemaphore thread_ready;
>>    
>>        GMainContext *worker_context;
>>        GMainLoop *compare_loop;
>> @@ -557,6 +558,8 @@ static void *colo_compare_thread(void *opaque)
>>                              (GSourceFunc)check_old_packet_regular, s, NULL);
>>        g_source_attach(timeout_source, s->worker_context);
>>    
>> +    qemu_sem_post(&s->thread_ready);
>> +
>>        g_main_loop_run(s->compare_loop);
>>    
>>        g_source_unref(timeout_source);
>> @@ -707,12 +710,15 @@ static void colo_compare_complete(UserCreatable *uc, Error **errp)
>>                                                          connection_key_equal,
>>                                                          g_free,
>>                                                          connection_destroy);
>> +    qemu_sem_init(&s->thread_ready, 0);
>>    
>>        sprintf(thread_name, "colo-compare %d", compare_id);
>>        qemu_thread_create(&s->thread, thread_name,
>>                           colo_compare_thread, s,
>>                           QEMU_THREAD_JOINABLE);
>>        compare_id++;
>> +    qemu_sem_wait(&s->thread_ready);
>> +    qemu_sem_destroy(&s->thread_ready);
>>    
>>        return;
>>    }
>
> .
>