Re: [PATCH 5/7] migration: Drop return code for disgard ram process

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

* Peter Xu (peterx@redhat.com) wrote:
> It will just never fail.  Drop those return values where they're constantly
> zeros.
> 
> A tiny touch-up on the tracepoint so trace_ram_postcopy_send_discard_bitmap()
> is called after the logic itself (which sounds more reasonable).
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>

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

> ---
>  migration/migration.c |  5 +----
>  migration/ram.c       | 20 +++++---------------
>  migration/ram.h       |  2 +-
>  3 files changed, 7 insertions(+), 20 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index abaf6f9e3d..c2e5539721 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2983,10 +2983,7 @@ static int postcopy_start(MigrationState *ms)
>       * that are dirty
>       */
>      if (migrate_postcopy_ram()) {
> -        if (ram_postcopy_send_discard_bitmap(ms)) {
> -            error_report("postcopy send discard bitmap failed");
> -            goto fail;
> -        }
> +        ram_postcopy_send_discard_bitmap(ms);
>      }
>  
>      /*
> diff --git a/migration/ram.c b/migration/ram.c
> index ecc744d54d..28f1ace0f7 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -2478,8 +2478,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, RAMBlock *block);
>  /**
>   * postcopy_each_ram_send_discard: discard all RAMBlocks
>   *
> - * Returns 0 for success or negative for error
> - *
>   * Utility for the outgoing postcopy code.
>   *   Calls postcopy_send_discard_bm_ram for each RAMBlock
>   *   passing it bitmap indexes and name.
> @@ -2488,10 +2486,9 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, RAMBlock *block);
>   *
>   * @ms: current migration state
>   */
> -static int postcopy_each_ram_send_discard(MigrationState *ms)
> +static void postcopy_each_ram_send_discard(MigrationState *ms)
>  {
>      struct RAMBlock *block;
> -    int ret;
>  
>      RAMBLOCK_FOREACH_NOT_IGNORED(block) {
>          postcopy_discard_send_init(ms, block->idstr);
> @@ -2509,14 +2506,9 @@ static int postcopy_each_ram_send_discard(MigrationState *ms)
>           * just needs indexes at this point, avoids it having
>           * target page specific code.
>           */
> -        ret = postcopy_send_discard_bm_ram(ms, block);
> +        postcopy_send_discard_bm_ram(ms, block);
>          postcopy_discard_send_finish(ms);
> -        if (ret) {
> -            return ret;
> -        }
>      }
> -
> -    return 0;
>  }
>  
>  /**
> @@ -2589,8 +2581,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, RAMBlock *block)
>  /**
>   * ram_postcopy_send_discard_bitmap: transmit the discard bitmap
>   *
> - * Returns zero on success
> - *
>   * Transmit the set of pages to be discarded after precopy to the target
>   * these are pages that:
>   *     a) Have been previously transmitted but are now dirty again
> @@ -2601,7 +2591,7 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, RAMBlock *block)
>   *
>   * @ms: current migration state
>   */
> -int ram_postcopy_send_discard_bitmap(MigrationState *ms)
> +void ram_postcopy_send_discard_bitmap(MigrationState *ms)
>  {
>      RAMState *rs = ram_state;
>  
> @@ -2615,9 +2605,9 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms)
>      rs->last_sent_block = NULL;
>      rs->last_page = 0;
>  
> -    trace_ram_postcopy_send_discard_bitmap();
> +    postcopy_each_ram_send_discard(ms);
>  
> -    return postcopy_each_ram_send_discard(ms);
> +    trace_ram_postcopy_send_discard_bitmap();
>  }
>  
>  /**
> diff --git a/migration/ram.h b/migration/ram.h
> index f543e25765..2c6dc3675d 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -57,7 +57,7 @@ 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 ram_postcopy_migrated_memory_release(MigrationState *ms);
>  /* For outgoing discard bitmap */
> -int ram_postcopy_send_discard_bitmap(MigrationState *ms);
> +void ram_postcopy_send_discard_bitmap(MigrationState *ms);
>  /* For incoming postcopy discard */
>  int ram_discard_range(const char *block_name, uint64_t start, size_t length);
>  int ram_postcopy_incoming_init(MigrationIncomingState *mis);
> -- 
> 2.32.0
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK