From 4333fb96ca1086d1cec0f93f78c453aa2dee8a5c Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Fri, 16 Aug 2019 13:01:22 -0300 Subject: media: lib/sort.c: implement sort() variant taking context argument Our list_sort() utility has always supported a context argument that is passed through to the comparison routine. Now there's a use case for the similar thing for sort(). This implements sort_r by simply extending the existing sort function in the obvious way. To avoid code duplication, we want to implement sort() in terms of sort_r(). The naive way to do that is static int cmp_wrapper(const void *a, const void *b, const void *ctx) { int (*real_cmp)(const void*, const void*) = ctx; return real_cmp(a, b); } sort(..., cmp) { sort_r(..., cmp_wrapper, cmp) } but this would do two indirect calls for each comparison. Instead, do as is done for the default swap functions - that only adds a cost of a single easily predicted branch to each comparison call. Aside from introducing support for the context argument, this also serves as preparation for patches that will eliminate the indirect comparison calls in common cases. Requested-by: Boris Brezillon Signed-off-by: Rasmus Villemoes Signed-off-by: Boris Brezillon Acked-by: Andrew Morton Tested-by: Philipp Zabel Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- include/linux/sort.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/sort.h') diff --git a/include/linux/sort.h b/include/linux/sort.h index 2b99a5dd073d..61b96d0ebc44 100644 --- a/include/linux/sort.h +++ b/include/linux/sort.h @@ -4,6 +4,11 @@ #include +void sort_r(void *base, size_t num, size_t size, + int (*cmp)(const void *, const void *, const void *), + void (*swap)(void *, void *, int), + const void *priv); + void sort(void *base, size_t num, size_t size, int (*cmp)(const void *, const void *), void (*swap)(void *, void *, int)); -- cgit v1.2.3