Re: [Qemu-devel] [PATCH] Wire g_new() and friends to the qemu_malloc() family

[Blue Swirl]

On Sun, Aug 21, 2011 at 3:11 AM, Anthony Liguori <address@hidden> wrote:
> On 08/20/2011 01:59 AM, Blue Swirl wrote:
>>
>> On Fri, Aug 19, 2011 at 3:22 PM, Avi Kivity<address@hidden>  wrote:
>>>
>>> On 08/18/2011 09:54 PM, Peter Maydell wrote:
>>>>
>>>> On 18 August 2011 18:48, Avi Kivity<address@hidden>    wrote:
>>>>>
>>>>>  +static GMemVTable gmemvtable = {
>>>>>  +    .malloc = qemu_malloc,
>>>>>  +    .realloc = qemu_realloc,
>>>>>  +    .free = qemu_free,
>>>>>  +};
>>>>>  +
>>>>>  +/**
>>>>>  + * qemu_malloc_init: initialize memory management
>>>>>  + */
>>>>>  +void qemu_malloc_init(void)
>>>>>  +{
>>>>>  +    g_mem_set_vtable(&gmemvtable);
>>>>>  +}
>>>>
>>>> Does this mean you can now safely allocate with g_malloc
>>>> and free with qemu_free, or is mixing the two APIs like that
>>>> still a no-no ?
>>>
>>> You can, but I'd forbid it.  Mixing layers can only lead to tears later
>>> on.
>>>
>>> Best would be to convert qemu_malloc()s to g_new()s and g_malloc()s to
>>> reduce confusion.
>>
>> Also plain malloc() and friends, except in tracing back end for obvious
>> reasons.
>
> sed script:
>
> s:qemu_mallocz\( *\)(:g_malloc0\1\(:g
> s:qemu_malloc\( *\)(:g_malloc\1\(:g
> s:qemu_free\( *\)(:g_free\1\(:g
> s:qemu_strdup\( *\)(:g_strdup\1\(:g
> s:qemu_strndup\( *\)(:g_strndup\1\(:g

nih--;

Too bad GLib does not provide a function which gives aligned memory,
then also qemu_memalign() and maybe qemu_vmalloc() could be replaced.

The next step (or merged with this step) should be to replace plain
libc malloc/free/asprintf/strdup with
g_malloc/g_free/g_strdup_printf/g_strdup.

HACKING should be updated to refer to g_* versions instead of qemu_* functions.

> It takes a little build magic too to make sure everything has access to
> glib.
>
> The patch is way too large to post.  Please speak now if you have an
> objection otherwise I'll commit in a couple days.
>
> http://repo.or.cz/w/qemu/aliguori.git/commit/5cc99cedb46b3916dae8a565d5ffc5fb2f2e9bd6
>
> If anyone wants to try it out first.

I didn't test it but looks reasonable.