Messages in this thread | | | Date | Thu, 15 Feb 2018 09:36:39 -0800 | From | Matthew Wilcox <> | Subject | Re: [PATCH v2 2/8] mm: Add kvmalloc_ab_c and kvzalloc_struct |
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On Wed, Feb 14, 2018 at 07:40:50PM -0800, Matthew Wilcox wrote: > > a_foo = kvzalloc_struct_buf(struct foo, struct bar, nr_bars); > > > > or, of course. > > > > a_foo = kvzalloc_struct_buf(typeof(*a_foo), typeof(a_foo->bar[0]), > > nr_bars); > > > > or whatever.
This version works, although it's more typing in the callers:
- attr_group = kvzalloc_struct(attr_group, attrs, i + 1, + attr_group = kvzalloc_struct(typeof(*attr_group), attrs, i + 1, GFP_KERNEL); ... - dev_dax = kvzalloc_struct(dev_dax, res, count, GFP_KERNEL); + dev_dax = kvzalloc_struct(struct dev_dax, res, count, GFP_KERNEL); ... -#define kvzalloc_struct(p, member, n, gfp) \ - (typeof(p))kvzalloc_ab_c(n, \ - sizeof(*(p)->member) + __must_be_array((p)->member), \ - offsetof(typeof(*(p)), member), gfp) +#define kvzalloc_struct(s, member, n, gfp) ({ \ + s *__p; \ + (s *)kvzalloc_ab_c(n, \ + sizeof(*(__p)->member) + __must_be_array((__p)->member),\ + offsetof(s, member), gfp); \ +})
Gives all the same checking as the current version, and doesn't involve passing an uninitialised pointer to the macro.
It also looks pretty similar:
p = kvzalloc(sizeof(*p), GFP_KERNEL); p = kvzalloc_struct(typeof(*p), array, count, GFP_KERNEL); p = kvzalloc_array(sizeof(*p), count);
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