Re: [PATCH v3] migration: Fix rare hang of migration_channel_read_peek()

On 2026-08-12 08:43, Peter Xu wrote:
> In an unlikely case, when a migration stream is attached to the destination
> QEMU and only send <4 bytes to the channel as magic, it's possible that
> migration_channel_read_peek() may spin forever.
> 
> Fix it by adding a manual sleep for partial read.
> 
> Since the path isn't attached to a coroutine, it means when partial read
> happens, there's yet not much we can do but hang the main thread, it will
> happen even for len==0 case.  It means monitors can hang due to this,
> either partial read or no data arrived (but connection established).
> 
> Leave this for later, the hope is this is extremely rare in production.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3889
> Reported-by: Feifan Qian <[email protected]>
> Cc: Daniel P. Berrangé <[email protected]>
> Signed-off-by: Peter Xu <[email protected]>
> ---
>  migration/channel.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)

Reviewed-by: Juraj Marcin <[email protected]>