[PATCH net-next v2 02/18] skbuff: allow 2-4-argument skb_frag_dma_map()

Alexander Lobakin
2024-10-15T14:54:21Z

skb_frag_dma_map(dev, frag, 0, skb_frag_size(frag), DMA_TO_DEVICE)
is repeated across dozens of drivers and really wants a shorthand.
Add a macro which will count args and handle all possible number
from 2 to 5. Semantics:

skb_frag_dma_map(dev, frag) ->
__skb_frag_dma_map(dev, frag, 0, skb_frag_size(frag), DMA_TO_DEVICE)

skb_frag_dma_map(dev, frag, offset) ->
__skb_frag_dma_map(dev, frag, offset, skb_frag_size(frag) - offset,
DMA_TO_DEVICE)

skb_frag_dma_map(dev, frag, offset, size) ->
__skb_frag_dma_map(dev, frag, offset, size, DMA_TO_DEVICE)

skb_frag_dma_map(dev, frag, offset, size, dir) ->
__skb_frag_dma_map(dev, frag, offset, size, dir)

No object code size changes for the existing callers. Users passing
less arguments also won't have bigger size comparing to the full
equivalent call.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
---
include/linux/skbuff.h | 31 ++++++++++++++++++++++++++-----
1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 48f1e0fa2a13..f187a2415fb8 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3642,7 +3642,7 @@ static inline void skb_frag_page_copy(skb_frag_t *fragto,
bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);

/**
- * skb_frag_dma_map - maps a paged fragment via the DMA API
+ * __skb_frag_dma_map - maps a paged fragment via the DMA API
* @dev: the device to map the fragment to
* @frag: the paged fragment to map
* @offset: the offset within the fragment (starting at the
@@ -3652,15 +3652,36 @@ bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
*
* Maps the page associated with @frag to @device.
*/
-static inline dma_addr_t skb_frag_dma_map(struct device *dev,
- const skb_frag_t *frag,
- size_t offset, size_t size,
- enum dma_data_direction dir)
+static inline dma_addr_t __skb_frag_dma_map(struct device *dev,
+ const skb_frag_t *frag,
+ size_t offset, size_t size,
+ enum dma_data_direction dir)
{
return dma_map_page(dev, skb_frag_page(frag),
skb_frag_off(frag) + offset, size, dir);
}

+#define skb_frag_dma_map(dev, frag, ...) \
+ CONCATENATE(_skb_frag_dma_map, \
+ COUNT_ARGS(__VA_ARGS__))(dev, frag, ##__VA_ARGS__)
+
+#define __skb_frag_dma_map1(dev, frag, offset, uf, uo) ({ \
+ const skb_frag_t *uf = (frag); \
+ size_t uo = (offset); \
+ \
+ __skb_frag_dma_map(dev, uf, uo, skb_frag_size(uf) - uo, \
+ DMA_TO_DEVICE); \
+})
+#define _skb_frag_dma_map1(dev, frag, offset) \
+ __skb_frag_dma_map1(dev, frag, offset, __UNIQUE_ID(frag_), \
+ __UNIQUE_ID(offset_))
+#define _skb_frag_dma_map0(dev, frag) \
+ _skb_frag_dma_map1(dev, frag, 0)
+#define _skb_frag_dma_map2(dev, frag, offset, size) \
+ __skb_frag_dma_map(dev, frag, offset, size, DMA_TO_DEVICE)
+#define _skb_frag_dma_map3(dev, frag, offset, size, dir) \
+ __skb_frag_dma_map(dev, frag, offset, size, dir)
+
static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
gfp_t gfp_mask)
{
--
2.46.2