Re: [Qemu-devel] [PATCH v1 01/17] qemu/obj_pool.h: introduce object allocation pool

[Michael S. Tsirkin]

On Tue, Aug 05, 2014 at 05:55:49AM -0600, Eric Blake wrote:
> On 08/04/2014 09:33 PM, Ming Lei wrote:
> > This patch introduces object allocation pool for speeding up
> > object allocation in fast path.
> > 
> > Signed-off-by: Ming Lei <address@hidden>
> > ---
> >  include/qemu/obj_pool.h |   64 
> > +++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 64 insertions(+)
> >  create mode 100644 include/qemu/obj_pool.h
> > 
> > diff --git a/include/qemu/obj_pool.h b/include/qemu/obj_pool.h
> > new file mode 100644
> > index 0000000..94b5f49
> > --- /dev/null
> > +++ b/include/qemu/obj_pool.h
> > @@ -0,0 +1,64 @@
> > +#ifndef QEMU_OBJ_POOL_HEAD
> > +#define QEMU_OBJ_POOL_HEAD
> 
> Missing copyright boilerplate.  According to LICENSE, that makes this
> file GPLv2+, but I'd much rather you make it explicit.
> 
> > +
> > +typedef struct {
> > +    unsigned int size;
> > +    unsigned int cnt;
> 
> size_t feels better for sizes.  int may be okay in this case, but
> definitely consider if size_t is appropriate.
> 
> > +
> > +    void **free_obj;
> > +    int free_idx;
> > +
> > +    char *objs;
> > +} ObjPool;
> > +
> > +static inline void obj_pool_init(ObjPool *op, void *objs_buf, void 
> > **free_objs,
> > +                                 unsigned int obj_size, unsigned cnt)
> > +{
> > +    int i;
> > +
> > +    op->objs = (char *)objs_buf;
> 
> Why the cast? This is C, not C++.

It's not needed in C++ either, right?

> > +    op->free_obj = free_objs;
> > +    op->size = obj_size;
> > +    op->cnt = cnt;
> > +
> > +    for (i = 0; i < op->cnt; i++) {
> > +        op->free_obj[i] = (void *)&op->objs[i * op->size];
> 
> Again, why the cast?
> 
> 
> > +static inline bool obj_pool_has_obj(ObjPool *op, void *obj)
> > +{
> > +    return op && (unsigned long)obj >= (unsigned long)&op->objs[0] &&
> > +           (unsigned long)obj <=
> > +           (unsigned long)&op->objs[(op->cnt - 1) * op->size];
> 
> uintptr_t, not unsigned long.  You are asking for problems on 64-bit
> mingw, where unsigned long is 32 bits but uintptr_t is 64 bits.
> 
> -- 
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>