Re: [Xen-devel] [PATCH 05/23] libxl: init: Provide a gc later in libxl_ctx_alloc

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2013-12-17 at 18:35 +0000, Ian Jackson wrote:
> Provide libxl__gc *gc for the second half of libxl_ctx_alloc.
> (For the first half of the function, gc is in scope but set to NULL.)

libxl uses -Wno-declaration-after-statement so it would be valid to just
declare it at the point it becomes valid, would avoid mistakes with
people adding uses before this point.

> This makes it possible to make gc-requiring calls.  For example, it
> makes error logging more convenient.
> 
> Make use of this by changing the logging calls to use the LOG*
> convenience macros.
> 
> Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
>  tools/libxl/libxl.c |   11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index e8ad610..cfd1435 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -25,6 +25,7 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
>                      unsigned flags, xentoollog_logger * lg)
>  {
>      libxl_ctx *ctx = NULL;
> +    libxl__gc gc_buf, *gc = NULL;
>      int rc;
>  
>      if (version != LIBXL_VERSION) { rc = ERROR_VERSION; goto out; }
> @@ -79,6 +80,9 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
>      }
>  
>      /* Now ctx is safe for ctx_free; failures simply set rc and "goto out" */
> +    LIBXL_INIT_GC(gc_buf,ctx);
> +    gc = &gc_buf;
> +    /* Now gc is useable */
>  
>      rc = libxl__atfork_init(ctx);
>      if (rc) goto out;
> @@ -88,8 +92,7 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
>  
>      ctx->xch = xc_interface_open(lg,lg,0);
>      if (!ctx->xch) {
> -        LIBXL__LOG_ERRNOVAL(ctx, LIBXL__LOG_ERROR, errno,
> -                        "cannot open libxc handle");
> +        LOGEV(ERROR, errno, "cannot open libxc handle");
>          rc = ERROR_FAIL; goto out;
>      }
>  
> @@ -97,8 +100,7 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
>      if (!ctx->xsh)
>          ctx->xsh = xs_domain_open();
>      if (!ctx->xsh) {
> -        LIBXL__LOG_ERRNOVAL(ctx, LIBXL__LOG_ERROR, errno,
> -                        "cannot connect to xenstore");
> +        LOGEV(ERROR, errno, "cannot connect to xenstore");
>          rc = ERROR_FAIL; goto out;
>      }
>  
> @@ -106,6 +108,7 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
>      return 0;
>  
>   out:
> +    if (gc) libxl__free_all(gc);
>      libxl_ctx_free(ctx);
>      *pctx = NULL;
>      return rc;



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