Re: [PATCH 04/17] migration/multifd: Set p->running = true in the right place

[Fabiano Rosas <farosas@suse.de>]

Avihai Horon <avihaih@nvidia.com> writes:

> The commit in the fixes line moved multifd thread creation to a
> different location, but forgot to move the p->running = true assignment
> as well. Thus, p->running is set to true before multifd thread is
> actually created.
>
> p->running is used in multifd_save_cleanup() to decide whether to join
> the multifd thread or not.
>
> With TLS, an error in multifd_tls_channel_connect() can lead to a
> segmentation fault because p->running is true but p->thread is never
> initialized, so multifd_save_cleanup() tries to join an uninitialized
> thread.
>
> Fix it by moving p->running = true assignment right after multifd thread
> creation. Also move qio_channel_set_delay() to there, as this is where
> it used to be originally.
>
> Fixes: 29647140157a ("migration/tls: add support for multifd tls-handshake")
> Signed-off-by: Avihai Horon <avihaih@nvidia.com>

Just for context, I haven't looked at this patch yet, but we were
planning to remove p->running altogether:

https://lore.kernel.org/r/20231110200241.20679-1-farosas@suse.de