sfc: Simplify TSO header buffer allocation

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TSO header buffers contain a control structure immediately followed by
the packet headers, and are kept on a free list when not in use.  This
complicates buffer management and tends to result in cache read misses
when we recycle such buffers (particularly if DMA-coherent memory
requires caches to be disabled).

Replace the free list with a simple mapping by descriptor index.  We
know that there is always a payload descriptor between any two
descriptors with TSO header buffers, so we can allocate only one
such buffer for each two descriptors.

While we're at it, use a standard error code for allocation failure,
not -1.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

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This commit is contained in:

Ben Hutchings 2012-05-17 18:40:54 +01:00

parent 14bf718fb9

commit f7251a9ce9

3 changed files with 112 additions and 218 deletions

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13

drivers/net/ethernet/sfc/net_driver.h

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2

drivers/net/ethernet/sfc/nic.c

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323

drivers/net/ethernet/sfc/tx.c

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