lib min_heap: add min_heap_sift_up()

Add min_heap_sift_up() to sift up the element at index 'idx' in the
heap.

Link: https://lkml.kernel.org/r/20240524152958.919343-10-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Coly Li <colyli@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Sakai <msakai@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/min_heap.h b/include/linux/min_heap.h
index 4acd0f4b3fafb73bfdf5258862820cb353fa54e4..ddd0186afb774c5fa2fa9129d23917d6942950ae 100644 (file)
--- a/include/linux/min_heap.h
+++ b/include/linux/min_heap.h
@@ -111,6 +111,26 @@ void __min_heapify(min_heap_char *heap, int pos, size_t elem_size,
 #define min_heapify(_heap, _pos, _func, _args) \
        __min_heapify((min_heap_char *)_heap, _pos, __minheap_obj_size(_heap), _func, _args)
 
+/* Sift up ith element from the heap, O(log2(nr)). */
+static __always_inline
+void __min_heap_sift_up(min_heap_char *heap, size_t elem_size, size_t idx,
+               const struct min_heap_callbacks *func, void *args)
+{
+       void *data = heap->data;
+       size_t parent;
+
+       while (idx) {
+               parent = (idx - 1) / 2;
+               if (func->less(data + parent * elem_size, data + idx * elem_size, args))
+                       break;
+               func->swp(data + parent * elem_size, data + idx * elem_size, args);
+               idx = parent;
+       }
+}
+
+#define min_heap_sift_up(_heap, _idx, _func, _args)    \
+       __min_heap_sift_up((min_heap_char *)_heap, __minheap_obj_size(_heap), _idx, _func, _args)
+
 /* Floyd's approach to heapification that is O(nr). */
 static __always_inline
 void __min_heapify_all(min_heap_char *heap, size_t elem_size,