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Message-ID: <84A937D219C2B44EB8EA44831ACA1E49166C7492@SC-MBX02-3.TheFacebook.com>
Date: Mon, 19 Nov 2012 09:52:33 +0000
From: Dan Williams <djbw@...com>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: "dwmw2@...radead.org" <dwmw2@...radead.org>,
"hskinnemoen@...il.com" <hskinnemoen@...il.com>,
"iws@...o.caltech.edu" <iws@...o.caltech.edu>,
"vinod.koul@...el.com" <vinod.koul@...el.com>,
"vipin.kumar@...com" <vipin.kumar@...com>,
"t.figa@...sung.com" <t.figa@...sung.com>,
"kyungmin.park@...sung.com" <kyungmin.park@...sung.com>
Subject: Re: [PATCH 13/20] async_tx: do DMA unmap in core for XOR operations
On 11/5/12 2:00 AM, "Bartlomiej Zolnierkiewicz" <b.zolnierkie@...sung.com>
wrote:
>In struct dma_async_tx_descriptor convert dma_[src,dst] fields to
>arrays and also add dma_src_cnt field. Then convert core async_tx
>code (do_async_xor()) to do DMA unmapping itself using the ->callback
>functionality.
>
>Cc: Dan Williams <djbw@...com>
>Cc: Tomasz Figa <t.figa@...sung.com>
>Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
>Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
>---
> crypto/async_tx/async_memcpy.c | 8 ++---
> crypto/async_tx/async_xor.c | 80
>+++++++++++++++++++++++++++++++-----------
> drivers/dma/dmaengine.c | 26 +++++++-------
> include/linux/dmaengine.h | 14 +++++---
> 4 files changed, 87 insertions(+), 41 deletions(-)
>
>diff --git a/crypto/async_tx/async_memcpy.c
>b/crypto/async_tx/async_memcpy.c
>index b6d5dab..cb0628e 100644
>--- a/crypto/async_tx/async_memcpy.c
>+++ b/crypto/async_tx/async_memcpy.c
>@@ -35,8 +35,8 @@ static void async_memcpy_cb(void *dma_async_param)
> struct dma_async_tx_descriptor *tx = dma_async_param;
> struct dma_device *dev = tx->chan->device;
>
>- dma_unmap_page(dev->dev, tx->dma_src, tx->dma_len, DMA_TO_DEVICE);
>- dma_unmap_page(dev->dev, tx->dma_dst, tx->dma_len, DMA_FROM_DEVICE);
>+ dma_unmap_page(dev->dev, tx->dma_src[0], tx->dma_len, DMA_TO_DEVICE);
>+ dma_unmap_page(dev->dev, tx->dma_dst[0], tx->dma_len, DMA_FROM_DEVICE);
>
> if (tx->orig_callback)
> tx->orig_callback(tx->orig_callback_param);
>@@ -91,8 +91,8 @@ async_memcpy(struct page *dest, struct page *src,
>unsigned int dest_offset,
> if (tx) {
> pr_debug("%s: (async) len: %zu\n", __func__, len);
>
>- tx->dma_src = dma_src;
>- tx->dma_dst = dma_dest;
>+ tx->dma_src[0] = dma_src;
>+ tx->dma_dst[0] = dma_dest;
> tx->dma_len = len;
>
> __async_tx_submit(chan, tx, async_memcpy_cb, tx, submit);
>diff --git a/crypto/async_tx/async_xor.c b/crypto/async_tx/async_xor.c
>index 154cc84..59a4af3 100644
>--- a/crypto/async_tx/async_xor.c
>+++ b/crypto/async_tx/async_xor.c
>@@ -31,6 +31,26 @@
> #include <linux/raid/xor.h>
> #include <linux/async_tx.h>
>
>+static void do_async_xor_cb(void *dma_async_param)
>+{
>+ struct dma_async_tx_descriptor *tx = dma_async_param;
>+ struct dma_device *dev = tx->chan->device;
>+ int i;
>+
>+ dma_unmap_page(dev->dev, tx->dma_dst[0], tx->dma_len,
>+ DMA_BIDIRECTIONAL);
>+
>+ for (i = 0; i < tx->dma_src_cnt; i++) {
>+ if (tx->dma_src[i] == tx->dma_dst[0])
>+ continue;
>+ dma_unmap_page(dev->dev, tx->dma_src[i], tx->dma_len,
>+ DMA_TO_DEVICE);
>+ }
>+
>+ if (tx->orig_callback)
>+ tx->orig_callback(tx->orig_callback_param);
>+}
>+
> /* do_async_xor - dma map the pages and perform the xor with an engine */
> static __async_inline struct dma_async_tx_descriptor *
> do_async_xor(struct dma_chan *chan, struct page *dest, struct page
>**src_list,
>@@ -39,42 +59,34 @@ do_async_xor(struct dma_chan *chan, struct page
>*dest, struct page **src_list,
> {
> struct dma_device *dma = chan->device;
> struct dma_async_tx_descriptor *tx = NULL;
>- int src_off = 0;
>- int i;
>+ int i, j;
> dma_async_tx_callback cb_fn_orig = submit->cb_fn;
> void *cb_param_orig = submit->cb_param;
> enum async_tx_flags flags_orig = submit->flags;
> enum dma_ctrl_flags dma_flags;
> int xor_src_cnt = 0;
>+ int src_list_cnt = 0;
>+ int extra_ent = 0;
> dma_addr_t dma_dest;
>
>- /* map the dest bidrectional in case it is re-used as a source */
>- dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_BIDIRECTIONAL);
> for (i = 0; i < src_cnt; i++) {
>- /* only map the dest once */
> if (!src_list[i])
> continue;
>- if (unlikely(src_list[i] == dest)) {
>- dma_src[xor_src_cnt++] = dma_dest;
>- continue;
>- }
>- dma_src[xor_src_cnt++] = dma_map_page(dma->dev, src_list[i], offset,
>- len, DMA_TO_DEVICE);
>+ xor_src_cnt++;
> }
> src_cnt = xor_src_cnt;
>
> while (src_cnt) {
> submit->flags = flags_orig;
>- dma_flags = 0;
>+ dma_flags = DMA_COMPL_SKIP_SRC_UNMAP |
>+ DMA_COMPL_SKIP_DEST_UNMAP;
> xor_src_cnt = min(src_cnt, (int)dma->max_xor);
>- /* if we are submitting additional xors, leave the chain open,
>- * clear the callback parameters, and leave the destination
>- * buffer mapped
>+ /* if we are submitting additional xors, leave the chain open
>+ * and clear the callback parameters
> */
> if (src_cnt > xor_src_cnt) {
> submit->flags &= ~ASYNC_TX_ACK;
> submit->flags |= ASYNC_TX_FENCE;
>- dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
> submit->cb_fn = NULL;
> submit->cb_param = NULL;
> } else {
>@@ -85,11 +97,32 @@ do_async_xor(struct dma_chan *chan, struct page
>*dest, struct page **src_list,
> dma_flags |= DMA_PREP_INTERRUPT;
> if (submit->flags & ASYNC_TX_FENCE)
> dma_flags |= DMA_PREP_FENCE;
>+
>+ /* map it bidirectional as it can be re-used as a source */
>+ dma_dest = dma_map_page(dma->dev, dest, offset, len,
>+ DMA_BIDIRECTIONAL);
This maps the destination unconditionally multiple times. More critically
it gets unmapped at the first completion, but it needs to remain mapped
until all operations complete.
So, we need a separate unmap object with a different lifetime than the
descriptor. I'm putting together some patches along those lines to
dynamically allocate some unmap data and hang it off the descriptor.
--
Dan
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