linux-kernel - Re: [PATCH 5/8] docs: dma-api: remove duplicate description of the DMA pool API

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5ea93880-72fa-46c7-b69b-82e2021aa567@infradead.org>
Date: Tue, 24 Jun 2025 19:40:37 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: Petr Tesarik <ptesarik@...e.com>, Jonathan Corbet <corbet@....net>,
 Morton <akpm@...ux-foundation.org>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
 Leon Romanovsky <leon@...nel.org>, Keith Busch <kbusch@...nel.org>,
 Caleb Sander Mateos <csander@...estorage.com>,
 Sagi Grimberg <sagi@...mberg.me>, Jens Axboe <axboe@...nel.dk>,
 John Garry <john.g.garry@...cle.com>,
 "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
 open list <linux-kernel@...r.kernel.org>,
 "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>
Subject: Re: [PATCH 5/8] docs: dma-api: remove duplicate description of the
 DMA pool API

Hi,

On 6/24/25 6:39 AM, Petr Tesarik wrote:
> The DMA pool API is documented in Memory Management APIs. Do not duplicate
> it in DMA API documentation.
> 

This looks like it works (from just visual inspection), but I'm wondering
why not just move all DMA API interfaces to dma-api.rst and don't have any
in mm-api.rst... ?

Thanks.

> Signed-off-by: Petr Tesarik <ptesarik@...e.com>
> ---
>  Documentation/core-api/dma-api.rst | 62 +-----------------------------
>  Documentation/core-api/mm-api.rst  |  2 +
>  2 files changed, 4 insertions(+), 60 deletions(-)
> 
> diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst
> index 3e89e3b0ecfd..f7fddaf7510c 100644
> --- a/Documentation/core-api/dma-api.rst
> +++ b/Documentation/core-api/dma-api.rst
> @@ -83,66 +83,8 @@ much like a struct kmem_cache, except that they use the DMA-coherent allocator,
>  not __get_free_pages().  Also, they understand common hardware constraints
>  for alignment, like queue heads needing to be aligned on N-byte boundaries.
>  
> -
> -::
> -
> -	struct dma_pool *
> -	dma_pool_create(const char *name, struct device *dev,
> -			size_t size, size_t align, size_t alloc);
> -
> -dma_pool_create() initializes a pool of DMA-coherent buffers
> -for use with a given device.  It must be called in a context which
> -can sleep.
> -
> -The "name" is for diagnostics (like a struct kmem_cache name); dev and size
> -are like what you'd pass to dma_alloc_coherent().  The device's hardware
> -alignment requirement for this type of data is "align" (which is expressed
> -in bytes, and must be a power of two).  If your device has no boundary
> -crossing restrictions, pass 0 for alloc; passing 4096 says memory allocated
> -from this pool must not cross 4KByte boundaries.
> -
> -::
> -
> -	void *
> -	dma_pool_zalloc(struct dma_pool *pool, gfp_t mem_flags,
> -		        dma_addr_t *handle)
> -
> -Wraps dma_pool_alloc() and also zeroes the returned memory if the
> -allocation attempt succeeded.
> -
> -
> -::
> -
> -	void *
> -	dma_pool_alloc(struct dma_pool *pool, gfp_t gfp_flags,
> -		       dma_addr_t *dma_handle);
> -
> -This allocates memory from the pool; the returned memory will meet the
> -size and alignment requirements specified at creation time.  Pass
> -GFP_ATOMIC to prevent blocking, or if it's permitted (not
> -in_interrupt, not holding SMP locks), pass GFP_KERNEL to allow
> -blocking.  Like dma_alloc_coherent(), this returns two values:  an
> -address usable by the CPU, and the DMA address usable by the pool's
> -device.
> -
> -::
> -
> -	void
> -	dma_pool_free(struct dma_pool *pool, void *vaddr,
> -		      dma_addr_t addr);
> -
> -This puts memory back into the pool.  The pool is what was passed to
> -dma_pool_alloc(); the CPU (vaddr) and DMA addresses are what
> -were returned when that routine allocated the memory being freed.
> -
> -::
> -
> -	void
> -	dma_pool_destroy(struct dma_pool *pool);
> -
> -dma_pool_destroy() frees the resources of the pool.  It must be
> -called in a context which can sleep.  Make sure you've freed all allocated
> -memory back to the pool before you destroy it.
> +See :ref:`Documentation/core-api/mm-api.rst <dma_pools>` for a detailed
> +description of the DMA pools API.
>  
>  
>  Part Ic - DMA addressing limitations
> diff --git a/Documentation/core-api/mm-api.rst b/Documentation/core-api/mm-api.rst
> index a61766328ac0..de0bab6e3fdd 100644
> --- a/Documentation/core-api/mm-api.rst
> +++ b/Documentation/core-api/mm-api.rst
> @@ -91,6 +91,8 @@ Memory pools
>  .. kernel-doc:: mm/mempool.c
>     :export:
>  
> +.. _dma_pools:
> +
>  DMA pools
>  =========
>  

-- 
~Randy