Re: [Qemu-devel] [PATCH v2 08/10] migration: No need to return the size of the cache

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

* Juan Quintela (quintela@redhat.com) wrote:
> After the previous commits, we make sure that the value passed is
> right, or we just drop an error.  So now we return if there is one
> error or we have setup correctly the value passed.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  migration/migration.c | 6 ++----
>  migration/ram.c       | 8 +++-----
>  migration/ram.h       | 2 +-
>  3 files changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 3feffb5e26..f3d4503ce2 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1371,14 +1371,12 @@ void qmp_migrate_cancel(Error **errp)
>  void qmp_migrate_set_cache_size(int64_t value, Error **errp)
>  {
>      MigrationState *s = migrate_get_current();
> -    int64_t new_size;
>  
> -    new_size = xbzrle_cache_resize(value, errp);
> -    if (new_size < 0) {
> +    if (xbzrle_cache_resize(value, errp) < 0) {

That's not consistent with the function below; it returns
'0 or negative' for error; this check only tests for negative
as an error.

Dave

>          return;
>      }
>  
> -    s->xbzrle_cache_size = new_size;
> +    s->xbzrle_cache_size = value;
>  }
>  
>  int64_t qmp_query_migrate_cache_size(Error **errp)
> diff --git a/migration/ram.c b/migration/ram.c
> index c84f22d759..ed4d3c6295 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -111,15 +111,15 @@ static void XBZRLE_cache_unlock(void)
>   * migration may be using the cache and might finish during this call,
>   * hence changes to the cache are protected by XBZRLE.lock().
>   *
> - * Returns the new_size or negative in case of error.
> + * Returns the 0 or negative in case of error.
>   *
>   * @new_size: new cache size
>   * @errp: set *errp if the check failed, with reason
>   */
> -int64_t xbzrle_cache_resize(int64_t new_size, Error **errp)
> +int xbzrle_cache_resize(int64_t new_size, Error **errp)
>  {
>      PageCache *new_cache;
> -    int64_t ret;
> +    int64_t ret = 0;
>  
>      /* Check for truncation */
>      if (new_size != (size_t)new_size) {
> @@ -152,8 +152,6 @@ int64_t xbzrle_cache_resize(int64_t new_size, Error **errp)
>          cache_fini(XBZRLE.cache);
>          XBZRLE.cache = new_cache;
>      }
> -
> -    ret = new_size;
>  out:
>      XBZRLE_cache_unlock();
>      return ret;
> diff --git a/migration/ram.h b/migration/ram.h
> index 511b3dc582..c8ae382b5b 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -35,7 +35,7 @@
>  extern MigrationStats ram_counters;
>  extern XBZRLECacheStats xbzrle_counters;
>  
> -int64_t xbzrle_cache_resize(int64_t new_size, Error **errp);
> +int xbzrle_cache_resize(int64_t new_size, Error **errp);
>  uint64_t ram_bytes_remaining(void);
>  uint64_t ram_bytes_total(void);
>  
> -- 
> 2.13.6
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK