Re: [Qemu-devel] [PATCH v3 03/12] dump-guest-memory: using static DumpState, add DumpStatus

[Paolo Bonzini <pbonzini@redhat.com>]

On 30/11/2015 12:32, Peter Xu wrote:
> Instead of malloc/free each time for DumpState, make it
> static. Added DumpStatus to show status for dump.
> 
> This is to be used for detach dump.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  dump.c                | 30 +++++++++++++++++++++++++++---
>  include/sysemu/dump.h |  2 ++
>  qapi-schema.json      | 18 ++++++++++++++++++
>  3 files changed, 47 insertions(+), 3 deletions(-)
> 
> diff --git a/dump.c b/dump.c
> index d79e0ed..c9ea878 100644
> --- a/dump.c
> +++ b/dump.c
> @@ -1418,6 +1418,24 @@ static void get_max_mapnr(DumpState *s)
>      s->max_mapnr = paddr_to_pfn(last_block->target_end);
>  }
>  
> +/* init dump state with specific status */
> +static void dump_state_prepare(DumpState *s, DumpStatus status)
> +{
> +    bzero(s, sizeof(*s));
> +    s->status = status;

Either use memcpy, or

    s = (DumpState) { .status = status };

The latter is C99 and it's quite common in QEMU.

> +}
> +
> +static DumpState *dump_state_get_global(void)

No need for dump_state_get_global, just use a static variable.  Then you
can use &dump_state in qmp_dump_guest_memory.

> +{
> +    static DumpState state;

You can also initialize it together with the definition, using

    static DumpState state = { .status = DUMP_STATUS_NONE };

> +    static bool init = false;
> +    if (!init) {
> +        dump_state_prepare(&state, DUMP_STATUS_NONE);
> +        init = true;
> +    }
> +    return &state;
> +}
> +
>  static void dump_init(DumpState *s, int fd, bool has_format,
>                        DumpGuestMemoryFormat format, bool paging, bool has_filter,
>                        int64_t begin, int64_t length, Error **errp)
> @@ -1647,13 +1665,14 @@ void qmp_dump_guest_memory(bool paging, const char *file,
>          return;
>      }
>  
> -    s = g_malloc0(sizeof(DumpState));
> +    s = dump_state_get_global();
> +    dump_state_prepare(s, DUMP_STATUS_ACTIVE);
>  
>      dump_init(s, fd, has_format, format, paging, has_begin,
>                begin, length, &local_err);
>      if (local_err) {
> -        g_free(s);
>          error_propagate(errp, local_err);
> +        s->status = DUMP_STATUS_FAILED;
>          return;
>      }
>  
> @@ -1663,8 +1682,13 @@ void qmp_dump_guest_memory(bool paging, const char *file,
>          create_vmcore(s, errp);
>      }
>  
> +    if (*errp) {
> +        s->status = DUMP_STATUS_FAILED;
> +    } else {
> +        s->status = DUMP_STATUS_COMPLETED;
> +    }
> +
>      dump_cleanup(s);
> -    g_free(s);
>  }
>  
>  DumpGuestMemoryCapability *qmp_query_dump_guest_memory_capability(Error **errp)
> diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
> index 7e4ec5c..affef38 100644
> --- a/include/sysemu/dump.h
> +++ b/include/sysemu/dump.h
> @@ -45,6 +45,7 @@
>  
>  #include "sysemu/dump-arch.h"
>  #include "sysemu/memory_mapping.h"
> +#include "qapi-types.h"
>  
>  typedef struct QEMU_PACKED MakedumpfileHeader {
>      char signature[16];     /* = "makedumpfile" */
> @@ -183,6 +184,7 @@ typedef struct DumpState {
>      off_t offset_page;          /* offset of page part in vmcore */
>      size_t num_dumpable;        /* number of page that can be dumped */
>      uint32_t flag_compress;     /* indicate the compression format */
> +    DumpStatus status;          /* current dump status */
>  } DumpState;
>  
>  uint16_t cpu_to_dump16(DumpState *s, uint16_t val);
> diff --git a/qapi-schema.json b/qapi-schema.json
> index fd81ce2..3728bfc 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -2139,6 +2139,24 @@
>              '*format': 'DumpGuestMemoryFormat'} }
>  
>  ##
> +# @DumpStatus
> +#
> +# Define the status for dump guest memory.
> +#
> +# @none: not started any dump-guest-memory yet.
> +#
> +# @active: there is one dump running in background.
> +#
> +# @completed: the last dump has finished sucessfully
> +#
> +# @failed: the last dump has failed.
> +#
> +# Since 2.6
> +##
> +{ 'enum': 'DumpStatus',
> +  'data': [ 'none', 'active', 'completed', 'failed' ] }
> +
> +##
>  # @DumpGuestMemoryCapability:
>  #
>  # A list of the available formats for dump-guest-memory
>