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Date: Thu, 06 Dec 2012 16:47:55 +0100
From: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To: Dan Williams <djbw@...com>
Cc: linux-kernel@...r.kernel.org, linux@....linux.org.uk,
Vinod Koul <vinod.koul@...el.com>,
Tomasz Figa <t.figa@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>, dave.jiang@...el.com
Subject: Re: [PATCH 03/12] dmaengine: reference counted unmap data
On Thursday 06 December 2012 10:25:26 Dan Williams wrote:
> hang a common 'unmap' object off of dma descriptors for the purpose of
> providing a unified unmapping interface. The lifetime of a mapping may
> span multiple descriptors, so these unmap objects are reference counted
> by related descriptor.
>
> Cc: Vinod Koul <vinod.koul@...el.com>
> Cc: Tomasz Figa <t.figa@...sung.com>
> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> Cc: Kyungmin Park <kyungmin.park@...sung.com>
> Signed-off-by: Dan Williams <djbw@...com>
> ---
> drivers/dma/dmaengine.c | 157 ++++++++++++++++++++++++++++++++++++++++++---
> include/linux/dmaengine.h | 3 +
> 2 files changed, 151 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index f3cadc6..00f0baf 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -62,6 +62,7 @@
> #include <linux/rculist.h>
> #include <linux/idr.h>
> #include <linux/slab.h>
> +#include <linux/mempool.h>
>
> static DEFINE_MUTEX(dma_list_mutex);
> static DEFINE_IDR(dma_idr);
> @@ -856,6 +857,131 @@ void dma_async_device_unregister(struct dma_device *device)
> }
> EXPORT_SYMBOL(dma_async_device_unregister);
>
> +struct dmaengine_unmap_pool {
> + struct kmem_cache *cache;
> + const char *name;
> + mempool_t *pool;
> + size_t size;
> +};
> +
> +#define __UNMAP_POOL(x) { .size = x, .name = "dmaengine-unmap-" __stringify(x) }
> +static struct dmaengine_unmap_pool unmap_pool[] = {
> + __UNMAP_POOL(2),
> + #if IS_ENABLED(ASYNC_TX_DMA)
> + __UNMAP_POOL(16),
> + __UNMAP_POOL(128),
> + __UNMAP_POOL(256),
> + #endif
> +};
> +
> +static struct dmaengine_unmap_pool *__get_unmap_pool(int nr)
> +{
> + int order = get_count_order(nr);
> +
> + switch (order) {
> + case 0 ... 1:
> + return &unmap_pool[0];
> + case 2 ... 4:
> + return &unmap_pool[1];
> + case 5 ... 7:
> + return &unmap_pool[2];
> + case 8:
> + return &unmap_pool[3];
> + default:
> + BUG();
> + return NULL;
> + }
> +
> +}
> +
> +static void dmaengine_unmap(struct kref *kref)
> +{
> + struct dmaengine_unmap_data *unmap = container_of(kref, typeof(*unmap), kref);
> + struct device *dev = unmap->dev;
> + int cnt, i;
> +
> + cnt = unmap->to_cnt;
> + for (i = 0; i < cnt; i++)
> + dma_unmap_page(dev, unmap->addr[i], unmap->len,
> + DMA_TO_DEVICE);
> + cnt += unmap->from_cnt;
> + for (; i < cnt; i++)
> + dma_unmap_page(dev, unmap->addr[i], unmap->len,
> + DMA_FROM_DEVICE);
> + cnt += unmap->bidi_cnt;
> + for (; i < cnt; i++)
> + dma_unmap_page(dev, unmap->addr[i], unmap->len,
> + DMA_BIDIRECTIONAL);
> + kmem_cache_free(__get_unmap_pool(cnt)->cache, unmap);
Shouldn't it call mempool_free() instead?
> +}
> +
> +void dmaengine_unmap_put(struct dmaengine_unmap_data *unmap)
> +{
> + if (unmap)
> + kref_put(&unmap->kref, dmaengine_unmap);
> +}
> +EXPORT_SYMBOL_GPL(dmaengine_unmap_put);
> +
> +static void dmaengine_destroy_unmap_pool(void)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(unmap_pool); i++) {
> + struct dmaengine_unmap_pool *p = &unmap_pool[i];
> +
> + if (p->cache)
> + kmem_cache_destroy(p->cache);
> + p->cache = NULL;
> + if (p->pool)
> + mempool_destroy(p->pool);
> + p->pool = NULL;
> + }
> +}
> +
> +static int dmaengine_init_unmap_pool(void)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(unmap_pool); i++) {
> + struct dmaengine_unmap_pool *p = &unmap_pool[i];
> + size_t size;
> +
> + size = sizeof(struct dmaengine_unmap_data) +
> + sizeof(dma_addr_t) * p->size;
> +
> + p->cache = kmem_cache_create(p->name, size, 0,
> + SLAB_HWCACHE_ALIGN, NULL);
> + if (!p->cache)
> + break;
> + p->pool = mempool_create_slab_pool(1, p->cache);
> + if (!p->pool)
> + break;
> + }
> +
> + if (i > ARRAY_SIZE(unmap_pool))
> + return 0;
> +
> + dmaengine_destroy_unmap_pool();
> + return -ENOMEM;
> +}
> +
> +static struct dmaengine_unmap_data *
> +dmaengine_get_unmap_data(struct device *dev, int nr, gfp_t flags)
> +{
> + struct dmaengine_unmap_data *unmap;
> +
> + unmap = mempool_alloc(__get_unmap_pool(nr)->pool, flags);
> + if (!unmap)
> + return NULL;
> + unmap->to_cnt = 0;
> + unmap->from_cnt = 0;
> + unmap->bidi_cnt = 0;
unmap->len is not initialized
> + kref_init(&unmap->kref);
> + unmap->dev = dev;
> +
> + return unmap;
> +}
> +
> /**
> * dma_async_memcpy_pg_to_pg - offloaded copy from page to page
> * @chan: DMA channel to offload copy to
> @@ -877,24 +1003,33 @@ dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
> {
> struct dma_device *dev = chan->device;
> struct dma_async_tx_descriptor *tx;
> - dma_addr_t dma_dest, dma_src;
> + struct dmaengine_unmap_data *unmap;
> dma_cookie_t cookie;
> unsigned long flags;
>
> - dma_src = dma_map_page(dev->dev, src_pg, src_off, len, DMA_TO_DEVICE);
> - dma_dest = dma_map_page(dev->dev, dest_pg, dest_off, len,
> - DMA_FROM_DEVICE);
> - flags = DMA_CTRL_ACK;
> - tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len, flags);
> + unmap = dmaengine_get_unmap_data(dev->dev, 2, GFP_NOIO);
> + if (!unmap)
> + return -ENOMEM;
> +
> + unmap->to_cnt = 1;
> + unmap->from_cnt = 1;
> + unmap->addr[0] = dma_map_page(dev->dev, src_pg, src_off, len,
> + DMA_TO_DEVICE);
> + unmap->addr[1] = dma_map_page(dev->dev, dest_pg, dest_off, len,
> + DMA_FROM_DEVICE);
unmap->len is not set anywhere
> + flags = DMA_CTRL_ACK | DMA_COMPL_SKIP_SRC_UNMAP |
> + DMA_COMPL_SKIP_DEST_UNMAP;
> + tx = dev->device_prep_dma_memcpy(chan, unmap->addr[1], unmap->addr[0],
> + len, flags);
>
> if (!tx) {
> - dma_unmap_page(dev->dev, dma_src, len, DMA_TO_DEVICE);
> - dma_unmap_page(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
> + dmaengine_unmap_put(unmap);
> return -ENOMEM;
> }
>
> - tx->callback = NULL;
> + dma_set_unmap(tx, unmap);
> cookie = tx->tx_submit(tx);
> + dmaengine_unmap_put(unmap);
>
> preempt_disable();
> __this_cpu_add(chan->local->bytes_transferred, len);
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung Poland R&D Center
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