Re: [Qemu-devel] [PATCH 02/14] add a version number to ram_list

[Paolo Bonzini <pbonzini@redhat.com>]

Il 21/09/2012 16:08, Juan Quintela ha scritto:
> From: Umesh Deshpande <udeshpan@redhat.com>
> 
> This will be used to detect if last_block might have become invalid
> across different calls to ram_save_live.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Umesh Deshpande <udeshpan@redhat.com>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  arch_init.c | 7 ++++++-
>  cpu-all.h   | 1 +
>  exec.c      | 4 ++++
>  3 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/arch_init.c b/arch_init.c
> index d96e888..eb33fdd 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -336,6 +336,7 @@ static RAMBlock *last_block;
>  static ram_addr_t last_offset;
>  static unsigned long *migration_bitmap;
>  static uint64_t migration_dirty_pages;
> +static uint32_t last_version;
> 
>  static inline bool migration_bitmap_test_and_reset_dirty(MemoryRegion *mr,
>                                                           ram_addr_t offset)
> @@ -406,7 +407,6 @@ static void migration_bitmap_sync(void)
>      }
>  }
> 
> -
>  /*
>   * ram_save_block: Writes a page of memory to the stream f
>   *
> @@ -558,6 +558,7 @@ static void reset_ram_globals(void)
>  {
>      last_block = NULL;
>      last_offset = 0;
> +    last_version = ram_list.version;
>      sort_ram_list();
>  }
> 
> @@ -613,6 +614,10 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
>      uint64_t expected_downtime;
>      MigrationState *s = migrate_get_current();
> 
> +    if (ram_list.version != last_version) {
> +        reset_ram_globals();
> +    }
> +
>      bytes_transferred_last = bytes_transferred;
>      bwidth = qemu_get_clock_ns(rt_clock);
> 

Assuming ram_save_iterate() will take the RAM lock throughout, that's ok.

> diff --git a/cpu-all.h b/cpu-all.h
> index 3e67019..6576229 100644
> --- a/cpu-all.h
> +++ b/cpu-all.h
> @@ -497,6 +497,7 @@ typedef struct RAMBlock {
> 
>  typedef struct RAMList {
>      uint8_t *phys_dirty;
> +    uint32_t version;
>      QLIST_HEAD(, RAMBlock) blocks_mru;
>      QLIST_HEAD(, RAMBlock) blocks;
>  } RAMList;
> diff --git a/exec.c b/exec.c
> index 0db2beb..e9d1509 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2583,6 +2583,8 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
>      QLIST_INSERT_HEAD(&ram_list.blocks, new_block, next);
>      QLIST_INSERT_HEAD(&ram_list.blocks_mru, new_block, next_mru);
> 
> +    ram_list.version++;
> +
>      ram_list.phys_dirty = g_realloc(ram_list.phys_dirty,
>                                         last_ram_offset() >> TARGET_PAGE_BITS);
>      memset(ram_list.phys_dirty + (new_block->offset >> TARGET_PAGE_BITS),
> @@ -2610,6 +2612,7 @@ void qemu_ram_free_from_ptr(ram_addr_t addr)
>          if (addr == block->offset) {
>              QLIST_REMOVE(block, next);
>              QLIST_REMOVE(block, next_mru);
> +            ram_list.version++;
>              g_free(block);
>              return;
>          }
> @@ -2624,6 +2627,7 @@ void qemu_ram_free(ram_addr_t addr)
>          if (addr == block->offset) {
>              QLIST_REMOVE(block, next);
>              QLIST_REMOVE(block, next_mru);
> +            ram_list.version++;
>              if (block->flags & RAM_PREALLOC_MASK) {
>                  ;
>              } else if (mem_path) {
> 

Reviewed-by: Paolo Bonzini <pbonzini@gnu.org>