Re: [PATCH v5 05/13] migration: qemu_file_set_blocking(): add errp parameter

[Peter Xu <peterx@redhat.com>]

On Tue, Sep 16, 2025 at 04:13:54PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> qemu_file_set_blocking() is a wrapper on qio_channel_set_blocking(),
> so let's passthrough the errp.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Dan, please still have a look at my reply, and if possible it'll be great
to touch up the commit message if you agree.

https://lore.kernel.org/all/aMlrVHYxhuj1TYYL@x1.local/

Not a big issue even without that, it's OK to me. I confess I do not expect
the assertions to trigger..

Acked-by: Peter Xu <peterx@redhat.com>

> ---
>  migration/colo.c         | 5 ++++-
>  migration/migration.c    | 8 +++++---
>  migration/postcopy-ram.c | 2 +-
>  migration/qemu-file.c    | 4 ++--
>  migration/qemu-file.h    | 2 +-
>  migration/savevm.c       | 4 ++--
>  6 files changed, 15 insertions(+), 10 deletions(-)
> 
> diff --git a/migration/colo.c b/migration/colo.c
> index e0f713c837..cf4d71d9ed 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -859,7 +859,10 @@ static void *colo_process_incoming_thread(void *opaque)
>       * coroutine, and here we are in the COLO incoming thread, so it is ok to
>       * set the fd back to blocked.
>       */
> -    qemu_file_set_blocking(mis->from_src_file, true);
> +    if (!qemu_file_set_blocking(mis->from_src_file, true, &local_err)) {
> +        error_report_err(local_err);
> +        goto out;
> +    }
>  
>      colo_incoming_start_dirty_log();
>  
> diff --git a/migration/migration.c b/migration/migration.c
> index 10c216d25d..e1ac4d73c2 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -951,7 +951,7 @@ static void migration_incoming_setup(QEMUFile *f)
>  
>      assert(!mis->from_src_file);
>      mis->from_src_file = f;
> -    qemu_file_set_blocking(f, false);
> +    qemu_file_set_blocking(f, false, &error_abort);
>  }
>  
>  void migration_incoming_process(void)
> @@ -971,7 +971,7 @@ static bool postcopy_try_recover(void)
>          /* This should be set already in migration_incoming_setup() */
>          assert(mis->from_src_file);
>          /* Postcopy has standalone thread to do vm load */
> -        qemu_file_set_blocking(mis->from_src_file, true);
> +        qemu_file_set_blocking(mis->from_src_file, true, &error_abort);
>  
>          /* Re-configure the return path */
>          mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
> @@ -4002,7 +4002,9 @@ void migration_connect(MigrationState *s, Error *error_in)
>      }
>  
>      migration_rate_set(rate_limit);
> -    qemu_file_set_blocking(s->to_dst_file, true);
> +    if (!qemu_file_set_blocking(s->to_dst_file, true, &local_err)) {
> +        goto fail;
> +    }
>  
>      /*
>       * Open the return path. For postcopy, it is used exclusively. For
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 45af9a361e..0172172343 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -1909,7 +1909,7 @@ void postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
>       * The new loading channel has its own threads, so it needs to be
>       * blocked too.  It's by default true, just be explicit.
>       */
> -    qemu_file_set_blocking(file, true);
> +    qemu_file_set_blocking(file, true, &error_abort);
>      mis->postcopy_qemufile_dst = file;
>      qemu_sem_post(&mis->postcopy_qemufile_dst_done);
>      trace_postcopy_preempt_new_channel();
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index d5c6e7ec61..0f4280df21 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -888,9 +888,9 @@ void qemu_put_counted_string(QEMUFile *f, const char *str)
>   *       both directions, and thus changing the blocking on the main
>   *       QEMUFile can also affect the return path.
>   */
> -void qemu_file_set_blocking(QEMUFile *f, bool block)
> +bool qemu_file_set_blocking(QEMUFile *f, bool block, Error **errp)
>  {
> -    qio_channel_set_blocking(f->ioc, block, NULL);
> +    return qio_channel_set_blocking(f->ioc, block, errp);
>  }
>  
>  /*
> diff --git a/migration/qemu-file.h b/migration/qemu-file.h
> index f5b9f430e0..c13c967167 100644
> --- a/migration/qemu-file.h
> +++ b/migration/qemu-file.h
> @@ -71,7 +71,7 @@ void qemu_file_set_error(QEMUFile *f, int ret);
>  int qemu_file_shutdown(QEMUFile *f);
>  QEMUFile *qemu_file_get_return_path(QEMUFile *f);
>  int qemu_fflush(QEMUFile *f);
> -void qemu_file_set_blocking(QEMUFile *f, bool block);
> +bool qemu_file_set_blocking(QEMUFile *f, bool block, Error **errp);
>  int qemu_file_get_to_fd(QEMUFile *f, int fd, size_t size);
>  void qemu_set_offset(QEMUFile *f, off_t off, int whence);
>  off_t qemu_get_offset(QEMUFile *f);
> diff --git a/migration/savevm.c b/migration/savevm.c
> index fabbeb296a..abe0547f9b 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2095,7 +2095,7 @@ static void *postcopy_ram_listen_thread(void *opaque)
>       * Because we're a thread and not a coroutine we can't yield
>       * in qemu_file, and thus we must be blocking now.
>       */
> -    qemu_file_set_blocking(f, true);
> +    qemu_file_set_blocking(f, true, &error_fatal);
>  
>      /* TODO: sanity check that only postcopiable data will be loaded here */
>      load_res = qemu_loadvm_state_main(f, mis);
> @@ -2108,7 +2108,7 @@ static void *postcopy_ram_listen_thread(void *opaque)
>      f = mis->from_src_file;
>  
>      /* And non-blocking again so we don't block in any cleanup */
> -    qemu_file_set_blocking(f, false);
> +    qemu_file_set_blocking(f, false, &error_fatal);
>  
>      trace_postcopy_ram_listen_thread_exit();
>      if (load_res < 0) {
> -- 
> 2.48.1
> 

-- 
Peter Xu