Re: [Qemu-devel] [PATCH 1/5] ram: Call migration_page_queue_free() at ram_migration_cleanup()

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> We shouldn't be using memory later than that.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>

Yes, I think I agree:

   migration_completion calls await_return_path_close_on_source that
makes sure there's no more incoming requests.

   migration_completion is called prior to the call to qemu_savevm_state_cleanup
qemu_savevm_state_cleanup calls the ram_migration_cleanup.

So you're moving it later which should be safe:


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

> ---
>  migration/migration.c | 2 --
>  migration/ram.c       | 5 +++--
>  migration/ram.h       | 1 -
>  3 files changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index af4c2cc..ea3d41c 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -814,8 +814,6 @@ static void migrate_fd_cleanup(void *opaque)
>      qemu_bh_delete(s->cleanup_bh);
>      s->cleanup_bh = NULL;
>  
> -    migration_page_queue_free();
> -
>      if (s->to_dst_file) {
>          trace_migrate_fd_cleanup();
>          qemu_mutex_unlock_iothread();
> diff --git a/migration/ram.c b/migration/ram.c
> index db7f4b0..e503277 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1181,10 +1181,9 @@ static bool get_queued_page(RAMState *rs, PageSearchStatus *pss)
>   * be some left.  in case that there is any page left, we drop it.
>   *
>   */
> -void migration_page_queue_free(void)
> +static void migration_page_queue_free(RAMState *rs)
>  {
>      struct RAMSrcPageRequest *mspr, *next_mspr;
> -    RAMState *rs = &ram_state;
>      /* This queue generally should be empty - but in the case of a failed
>       * migration might have some droppings in.
>       */
> @@ -1434,6 +1433,7 @@ void free_xbzrle_decoded_buf(void)
>  
>  static void ram_migration_cleanup(void *opaque)
>  {
> +    RAMState *rs = opaque;
>      RAMBlock *block;
>  
>      /* caller have hold iothread lock or is in a bh, so there is
> @@ -1459,6 +1459,7 @@ static void ram_migration_cleanup(void *opaque)
>          XBZRLE.current_buf = NULL;
>      }
>      XBZRLE_cache_unlock();
> +    migration_page_queue_free(rs);
>  }
>  
>  static void ram_state_reset(RAMState *rs)
> diff --git a/migration/ram.h b/migration/ram.h
> index c9563d1..d4da419 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -53,7 +53,6 @@ void migrate_decompress_threads_create(void);
>  void migrate_decompress_threads_join(void);
>  
>  uint64_t ram_pagesize_summary(void);
> -void migration_page_queue_free(void);
>  int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len);
>  void acct_update_position(QEMUFile *f, size_t size, bool zero);
>  void free_xbzrle_decoded_buf(void);
> -- 
> 2.9.4
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK