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authorTejun Heo <htejun@gmail.com>2008-07-19 23:03:35 +0900
committerPierre Ossman <drzeus@drzeus.cx>2008-07-23 14:42:09 +0200
commit137d3edb48425f82a6a4226b664f90ed5e42eea5 (patch)
tree0fc5845a0082686f0c5ebc87c9e48ac34e6265b7 /kernel
parent60c9c7b1d91396f511e55a2a5be13d148dcf66ff (diff)
sg: reimplement sg mapping iterator
This is alternative implementation of sg content iterator introduced by commit 83e7d317... from Pierre Ossman in next-20080716. As there's already an sg iterator which iterates over sg entries themselves, name this sg_mapping_iterator. Slightly edited description from the original implementation follows. Iteration over a sg list is not that trivial when you take into account that memory pages might have to be mapped before being used. Unfortunately, that means that some parts of the kernel restrict themselves to directly accesible memory just to not have to deal with the mess. This patch adds a simple iterator system that allows any code to easily traverse an sg list and not have to deal with all the details. The user can decide to consume part of the iteration. Also, iteration can be stopped and resumed later if releasing the kmap between iteration steps is necessary. These features are useful to implement piecemeal sg copying for interrupt drive PIO for example. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Diffstat (limited to 'kernel')
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