On Wed, Mar 13, 2024 at 06:28:24PM -0300, Fabiano Rosas wrote:
> When doing migration using the fd: URI, the incoming migration starts
> before the user has passed the file descriptor to QEMU. This means
> that the checks at migration_channels_and_transport_compatible()
> happen too soon and we need to allow a migration channel of type
> SOCKET_ADDRESS_TYPE_FD even though socket migration is not supported
> with multifd.
Hmm, bare with me if this is a stupid one.. why the incoming migration can
start _before_ the user passed in the fd?
IOW, why can't we rely on a single fd_is_socket() check for
SOCKET_ADDRESS_TYPE_FD in transport_supports_multi_channels()?
>
> The commit decdc76772 ("migration/multifd: Add mapped-ram support to
> fd: URI") was supposed to add a second check prior to starting
> migration to make sure a socket fd is not passed instead of a file fd,
> but failed to do so.
>
> Add the missing verification.
>
> Fixes: decdc76772 ("migration/multifd: Add mapped-ram support to fd: URI")
> Signed-off-by: Fabiano Rosas <faro...@suse.de>
> ---
> migration/fd.c | 8 ++++++++
> migration/file.c | 7 +++++++
> 2 files changed, 15 insertions(+)
>
> diff --git a/migration/fd.c b/migration/fd.c
> index 39a52e5c90..c07030f715 100644
> --- a/migration/fd.c
> +++ b/migration/fd.c
> @@ -22,6 +22,7 @@
> #include "migration.h"
> #include "monitor/monitor.h"
> #include "io/channel-file.h"
> +#include "io/channel-socket.h"
> #include "io/channel-util.h"
> #include "options.h"
> #include "trace.h"
> @@ -95,6 +96,13 @@ void fd_start_incoming_migration(const char *fdname, Error
> **errp)
> }
>
> if (migrate_multifd()) {
> + if (fd_is_socket(fd)) {
> + error_setg(errp,
> + "Multifd migration to a socket FD is not supported");
> + object_unref(ioc);
> + return;
> + }
> +
> file_create_incoming_channels(ioc, errp);
> } else {
> qio_channel_set_name(ioc, "migration-fd-incoming");
> diff --git a/migration/file.c b/migration/file.c
> index ddde0ca818..b6e8ba13f2 100644
> --- a/migration/file.c
> +++ b/migration/file.c
> @@ -15,6 +15,7 @@
> #include "file.h"
> #include "migration.h"
> #include "io/channel-file.h"
> +#include "io/channel-socket.h"
> #include "io/channel-util.h"
> #include "options.h"
> #include "trace.h"
> @@ -58,6 +59,12 @@ bool file_send_channel_create(gpointer opaque, Error
> **errp)
> int fd = fd_args_get_fd();
>
> if (fd && fd != -1) {
> + if (fd_is_socket(fd)) {
> + error_setg(errp,
> + "Multifd migration to a socket FD is not supported");
> + goto out;
> + }
> +
> ioc = qio_channel_file_new_dupfd(fd, errp);
> } else {
> ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, errp);
> --
> 2.35.3
>
--
Peter Xu
