Re: [PATCH v2 01/15] migration: Take bitmap mutex when completing ram migration

[Dr. David Alan Gilbert]

* Peter Xu (peterx@redhat.com) wrote:
> Any call to ram_find_and_save_block() needs to take the bitmap mutex.  We
> used to not take it for most of ram_save_complete() because we thought
> we're the only one left using the bitmap, but it's not true after the
> preempt full patchset applied, since the return path can be taking it too.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  migration/ram.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 1338e47665..cfeb571800 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -3406,6 +3406,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
>          /* try transferring iterative blocks of memory */
>  
>          /* flush all remaining blocks regardless of rate limiting */
> +        qemu_mutex_lock(&rs->bitmap_mutex);
>          while (true) {
>              int pages;
>  
> @@ -3419,6 +3420,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
>                  break;
>              }
>          }
> +        qemu_mutex_unlock(&rs->bitmap_mutex);
>  
>          flush_compressed_data(rs);
>          ram_control_after_iterate(f, RAM_CONTROL_FINISH);
> -- 
> 2.37.3
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK