Re: [PATCH 3/5] Migration thread mutex

Stefan Hajnoczi
2011-08-29T09:04:56Z

On Sat, Aug 27, 2011 at 7:09 PM, Umesh Deshpande <udeshpan@redhat.com> wrote:
> This patch implements migrate_ram mutex, which protects the RAMBlock list
> traversal in the migration thread during the transfer of a ram from their
> addition/removal from the iothread.
>
> Note: Combination of iothread mutex and migration thread mutex works as a
> rw-lock. Both mutexes are acquired while modifying the ram_list members or RAM
> block list.
>
> Signed-off-by: Umesh Deshpande <udeshpan@redhat.com>
> ---
>  arch_init.c   |   21 +++++++++++++++++++++
>  cpu-all.h     |    3 +++
>  exec.c        |   23 +++++++++++++++++++++++
>  qemu-common.h |    2 ++
>  4 files changed, 49 insertions(+), 0 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index 484b39d..9d02270 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -109,6 +109,7 @@ static int is_dup_page(uint8_t *page, uint8_t ch)
>
>  static RAMBlock *last_block;
>  static ram_addr_t last_offset;
> +static uint64_t last_version;
[...]
>  typedef struct RAMList {
> +    QemuMutex mutex;    /* Protects RAM block list */
>     uint8_t *phys_dirty;
> +    uint32_t version;   /* To detect ram block addition/removal */

Is there a reason why RAMList.version is uint32_t but last_version is uint64_t?

Stefan