[Qemu-devel] [PATCH 1/1] vl.c: don't try to insert malloc tracepoints on newer glib

[Qemu-devel] [PATCH 1/1] vl.c: don't try to insert malloc tracepoints on newer glib

[Serge Hallyn]

Because it has deprecated it with commit
3be6ed60aa58095691bd697344765e715a327fc1.  This prevents the warning

(process:3535): GLib-WARNING **: /build/glib2.0-3tdlHy/glib2.0-2.45.6/./glib/gmem.c:482: custom memory allocation vtable not supported

as reported at https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1491972

(thanks danpb for the suggestion)

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
---
 vl.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/vl.c b/vl.c
index 584ca88..cab9425 100644
--- a/vl.c
+++ b/vl.c
@@ -2719,6 +2719,7 @@ static const QEMUOption *lookup_opt(int argc, char **argv,
     return popt;
 }
 
+#if ! GLIB_CHECK_VERSION(2, 44, 0)
 static gpointer malloc_and_trace(gsize n_bytes)
 {
     void *ptr = malloc(n_bytes);
@@ -2738,6 +2739,7 @@ static void free_and_trace(gpointer mem)
     trace_g_free(mem);
     free(mem);
 }
+#endif
 
 static int machine_set_property(void *opaque,
                                 const char *name, const char *value,
@@ -2966,11 +2968,13 @@ int main(int argc, char **argv, char **envp)
     bool userconfig = true;
     const char *log_mask = NULL;
     const char *log_file = NULL;
+#if ! GLIB_CHECK_VERSION(2, 44, 0)
     GMemVTable mem_trace = {
         .malloc = malloc_and_trace,
         .realloc = realloc_and_trace,
         .free = free_and_trace,
     };
+#endif
     const char *trace_events = NULL;
     const char *trace_file = NULL;
     ram_addr_t maxram_size;
@@ -2986,7 +2990,9 @@ int main(int argc, char **argv, char **envp)
     error_set_progname(argv[0]);
     qemu_init_exec_dir(argv[0]);
 
+#if ! GLIB_CHECK_VERSION(2, 44, 0)
     g_mem_set_vtable(&mem_trace);
+#endif
 
     module_call_init(MODULE_INIT_QOM);
 
-- 
2.5.0

Re: [Qemu-devel] [PATCH 1/1] vl.c: don't try to insert malloc tracepoints on newer glib

[Peter Maydell]

On 4 September 2015 at 18:58, Serge Hallyn <serge.hallyn@ubuntu.com> wrote:
> Because it has deprecated it with commit
> 3be6ed60aa58095691bd697344765e715a327fc1.  This prevents the warning
>
> (process:3535): GLib-WARNING **: /build/glib2.0-3tdlHy/glib2.0-2.45.6/./glib/gmem.c:482: custom memory allocation vtable not supported
>
> as reported at https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1491972
>
> (thanks danpb for the suggestion)
>
> Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
> ---
>  vl.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/vl.c b/vl.c
> index 584ca88..cab9425 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2719,6 +2719,7 @@ static const QEMUOption *lookup_opt(int argc, char **argv,
>      return popt;
>  }
>
> +#if ! GLIB_CHECK_VERSION(2, 44, 0)

Existing style for these checks doesn't have a space
between the "!" and the "GLIB_CHECK_VERSION".

>  static gpointer malloc_and_trace(gsize n_bytes)
>  {
>      void *ptr = malloc(n_bytes);
> @@ -2738,6 +2739,7 @@ static void free_and_trace(gpointer mem)
>      trace_g_free(mem);
>      free(mem);
>  }
> +#endif

We could reduce the number of ifdefs we have to have here by
having inside this #if...

void register_glib_mem_trace_functions(void)

(with the GMemVTable and the call to g_mem_set_vtable in it),
and then having an
#else
    void register_glib_mem_trace_functions(void)
    {
        /* Newer versions of glib don't support intercepting the
         * memory allocation functions.
         */
    }
#endif

Then you can make the callsite un-ifdefed.

thanks
-- PMM