Messages in this thread | | | Date | Thu, 5 Mar 2020 16:42:33 +0100 | From | Christoph Hellwig <> | Subject | Re: [rfc 2/6] dma-remap: add additional atomic pools to map to gfp mask |
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On Sun, Mar 01, 2020 at 04:05:13PM -0800, David Rientjes wrote: > The single atomic pool is allocated from the lowest zone possible since > it is guaranteed to be applicable for any DMA allocation. > > Devices may allocate through the DMA API but not have a strict reliance > on GFP_DMA memory. Since the atomic pool will be used for all > non-blockable allocations, returning all memory from ZONE_DMA may > unnecessarily deplete the zone. > > Provision for multiple atomic pools that will map to the optimal gfp > mask of the device. These will be wired up in a subsequent patch. > > Signed-off-by: David Rientjes <rientjes@google.com> > --- > kernel/dma/remap.c | 75 +++++++++++++++++++++++++++------------------- > 1 file changed, 45 insertions(+), 30 deletions(-) > > diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c > --- a/kernel/dma/remap.c > +++ b/kernel/dma/remap.c > @@ -100,6 +100,8 @@ void dma_common_free_remap(void *cpu_addr, size_t size) > > #ifdef CONFIG_DMA_DIRECT_REMAP > static struct gen_pool *atomic_pool __ro_after_init; > +static struct gen_pool *atomic_pool_dma32 __ro_after_init; > +static struct gen_pool *atomic_pool_normal __ro_after_init;
Maybe rename atomic_pool as well as it really kinda looks like the default at the moment?
> > #define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K > static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE; > @@ -111,66 +113,79 @@ static int __init early_coherent_pool(char *p) > } > early_param("coherent_pool", early_coherent_pool); > > -static gfp_t dma_atomic_pool_gfp(void) > +static int __init __dma_atomic_pool_init(struct gen_pool **pool, > + size_t pool_size, gfp_t gfp) > {
Can this just return the pool and return NULL (or an ERR_PTR) on failure?
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