[Qemu-devel] Re: [PATCH 2/5] Add map client retry notification

[Anthony Liguori <anthony@codemonkey.ws>]

Avi Kivity wrote:
> The target memory mapping API may fail if the bounce buffer resources
> are exhausted.  Add a notification mechanism to allow clients to retry
> the mapping operation when resources become available again.
>
> Signed-off-by: Avi Kivity <avi@redhat.com>
>   

Fantastic!  Clearly, I should have read the next patch before responding 
to the first.

Regards,

Anthony Liguori

> ---
>  cpu-all.h |    3 +++
>  exec.c    |   38 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+), 0 deletions(-)
>
> diff --git a/cpu-all.h b/cpu-all.h
> index 3439999..67e795e 100644
> --- a/cpu-all.h
> +++ b/cpu-all.h
> @@ -928,6 +928,9 @@ void *cpu_physical_memory_map(target_phys_addr_t addr,
>                                int is_write);
>  void cpu_physical_memory_unmap(void *buffer, target_phys_addr_t len,
>                                 int is_write);
> +void *cpu_register_map_client(void *opaque, void (*callback)(void *opaque));
> +void cpu_unregister_map_client(void *cookie);
> +
>  uint32_t ldub_phys(target_phys_addr_t addr);
>  uint32_t lduw_phys(target_phys_addr_t addr);
>  uint32_t ldl_phys(target_phys_addr_t addr);
> diff --git a/exec.c b/exec.c
> index 7162271..62bedc0 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -3053,6 +3053,43 @@ typedef struct {
>  
>  static BounceBuffer bounce;
>  
> +typedef struct MapClient {
> +    void *opaque;
> +    void (*callback)(void *opaque);
> +    LIST_ENTRY(MapClient) link;
> +} MapClient;
> +
> +static LIST_HEAD(map_client_list, MapClient) map_client_list
> +    = LIST_HEAD_INITIALIZER(map_client_list);
> +
> +void *cpu_register_map_client(void *opaque, void (*callback)(void *opaque))
> +{
> +    MapClient *client = qemu_malloc(sizeof(*client));
> +
> +    client->opaque = opaque;
> +    client->callback = callback;
> +    LIST_INSERT_HEAD(&map_client_list, client, link);
> +    return client;
> +}
> +
> +void cpu_unregister_map_client(void *_client)
> +{
> +    MapClient *client = (MapClient *)_client;
> +
> +    LIST_REMOVE(client, link);
> +}
> +
> +static void cpu_notify_map_clients(void)
> +{
> +    MapClient *client;
> +
> +    while (!LIST_EMPTY(&map_client_list)) {
> +        client = LIST_FIRST(&map_client_list);
> +        client->callback(client->opaque);
> +        LIST_REMOVE(client, link);
> +    }
> +}
> +
>  void *cpu_physical_memory_map(target_phys_addr_t addr,
>                                target_phys_addr_t *plen,
>                                int is_write)
> @@ -3137,6 +3174,7 @@ void cpu_physical_memory_unmap(void *buffer, target_phys_addr_t len,
>      }
>      qemu_free(bounce.buffer);
>      bounce.buffer = NULL;
> +    cpu_notify_map_clients();
>  }
>  
>  /* warning: addr must be aligned */
>