Re: [PATCH] lib/genalloc: Set chunk size to real size which gen_pool managed.

From: chi wu
Date: Wed Jun 15 2022 - 08:41:51 EST


Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> 于2022年6月15日周三 01:53写道:
>
> On Tue, 14 Jun 2022 13:20:08 +0800 chi wu <wuchi.zero@xxxxxxxxx> wrote:
>
> > > If we're going to do this then gen_pool_add_owner() no longer needs its
> > > `size' argument.
> > >
> > >
> > Sorry, What point did I misunderstand?
>
> I mean we can now do this:
>
> --- a/lib/genalloc.c~lib-genalloc-set-chunk-size-to-real-size-which-gen_pool-managed-fix
> +++ a/lib/genalloc.c
> @@ -181,13 +181,14 @@ EXPORT_SYMBOL(gen_pool_create);
> *
> * Returns 0 on success or a -ve errno on failure.
> */
> -int gen_pool_add_owner(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
> - size_t size, int nid, void *owner)
> +int gen_pool_add_owner(struct gen_pool *pool, unsigned long virt,
> + phys_addr_t phys, int nid, void *owner)
> {
> struct gen_pool_chunk *chunk;
> unsigned long nbits = size >> pool->min_alloc_order; [1]

The arg @size is in bytes of the memory chunk to add to pool, we
really need that, [1] here we
get nbits by size. [2] later we will alloc bitmap by nbits... If we
remove the arg @size, we will
have no way to get the size of memory which we will manage.

> unsigned long nbytes = sizeof(struct gen_pool_chunk) +
> BITS_TO_LONGS(nbits) * sizeof(long); [1]
> + size_t size;
>
> chunk = vzalloc_node(nbytes, nid);
> if (unlikely(chunk == NULL))
> _
>

Thanks for Andrew's time