On Tue, Feb 09, 2021 at 03:52:51PM +0800, Hao Wang wrote:
> If any error happens during multifd send thread creating (e.g. channel broke
> because new domain is destroyed by the dst), multifd_tls_handshake_thread
> may exit silently, leaving main migration thread hanging (ram_save_setup ->
> multifd_send_sync_main -> qemu_sem_wait(&p->sem_sync)).
> Fix that by adding error handling in multifd_tls_handshake_thread.
>
> Signed-off-by: Hao Wang <wanghao...@huawei.com>
> ---
> migration/multifd.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 45c690aa11..df29cdd26a 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -736,7 +736,16 @@ static void multifd_tls_outgoing_handshake(QIOTask *task,
> } else {
> trace_multifd_tls_outgoing_handshake_complete(ioc);
> }
> - multifd_channel_connect(p, ioc, err);
> +
> + if (multifd_channel_connect(p, ioc, err)) {
Urgh, this method is rather confusing usng "true" to indicate failure.
In include/qapi/error.h we document
• bool-valued functions return true on success / false on failure,
Admittedly this problem is pre-existing before this patch, but I
would none the less like to see a patch that fixes thse inverted
semantics first, and then this as a subsequent patch on top.
> + /*
> + * Error happen, mark multifd_send_thread status as 'quit' although
> it
> + * is not created, and then tell who pay attention to me.
> + */
> + p->quit = true;
> + qemu_sem_post(&multifd_send_state->channels_ready);
> + qemu_sem_post(&p->sem_sync);
> + }
> }
>
> static void *multifd_tls_handshake_thread(void *opaque)
Regards,
Daniel
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