lkml.org 
[lkml]   [2020]   [Sep]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH] cma: make number of CMA areas dynamic, remove CONFIG_CMA_AREAS
From
Date
On 9/15/20 9:32 PM, Christoph Hellwig wrote:
> On Wed, Sep 02, 2020 at 08:02:04PM -0700, Mike Kravetz wrote:
>> --- a/arch/arm/mm/dma-mapping.c
>> +++ b/arch/arm/mm/dma-mapping.c
>> @@ -383,25 +383,34 @@ postcore_initcall(atomic_pool_init);
>> struct dma_contig_early_reserve {
>> phys_addr_t base;
>> unsigned long size;
>> + struct list_head areas;
>> };
>>
>> +static __initdata LIST_HEAD(dma_mmu_remap_areas);
>>
>> void __init dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
>> {
>> + struct dma_contig_early_reserve *d;
>> +
>> + d = memblock_alloc(sizeof(struct dma_contig_early_reserve),
>> + sizeof(void *));
>> + if (!d) {
>> + pr_err("Unable to allocate dma_contig_early_reserve struct!\n");
>> + return;
>> + }
>> +
>> + d->base = base;
>> + d->size = size;
>> + list_add_tail(&d->areas, &dma_mmu_remap_areas);
>> }
>
> I wonder if struct cma should grow a flags or type field, so that the
> arm code can simply use cma_for_each_area to iterate the CMA areas for
> the DMA fixup, and we can remove the extra list and the magic hook.

I will look into a way of doing that.

>
>> +/* modify here */
>> +LIST_HEAD(cma_areas);
>
> What does this comment mean?

Sorry, that might have been a note to myself that was accidentally left.

>
>> +static unsigned int cma_area_count;
>
> It seems this is only used to provide a default name for the CMA
> areas, but all areas actually provide a name, so I think we can drop
> the default naming and the cma_area_count variable entirely.
>

Seems reasonable.
We can change behavior to require a name.

>> if (!size || !memblock_is_region_reserved(base, size))
>> return -EINVAL;
>>
>> +
>> /* ensure minimal alignment required by mm core */
>
> This adds a spurious empty line.

yes, my bad.

>> static int __init cma_debugfs_init(void)
>> {
>> struct dentry *cma_debugfs_root;
>> - int i;
>> + struct cma *c;
>>
>> cma_debugfs_root = debugfs_create_dir("cma", NULL);
>>
>> - for (i = 0; i < cma_area_count; i++)
>> - cma_debugfs_add_one(&cma_areas[i], cma_debugfs_root);
>> + list_for_each_entry(c, &cma_areas, areas)
>> + cma_debugfs_add_one(c, cma_debugfs_root);
>
> I think this should use cma_for_each_area, that way cma_areas can be
> keep static in cma.c.

Yes, will provide a cma_for_each_area routine.

--
Mike Kravetz

\
 
 \ /
  Last update: 2020-09-16 22:16    [W:0.367 / U:7.812 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site