lib min_heap: add min_heap_del()

Add min_heap_del() to delete the element at index 'idx' in the heap.

Link: https://lkml.kernel.org/r/20240524152958.919343-11-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 ddd0186afb774c5fa2fa9129d23917d6942950ae..98e838195e7ee000f68d570175310722fdc3c456 100644 (file)
--- a/include/linux/min_heap.h
+++ b/include/linux/min_heap.h
@@ -212,4 +212,28 @@ void __min_heap_push(min_heap_char *heap, const void *element, size_t elem_size,
 #define min_heap_push(_heap, _element, _func, _args)   \
        __min_heap_push((min_heap_char *)_heap, _element, __minheap_obj_size(_heap), _func, _args)
 
+/* Remove ith element from the heap, O(log2(nr)). */
+static __always_inline
+bool __min_heap_del(min_heap_char *heap, size_t elem_size, size_t idx,
+               const struct min_heap_callbacks *func, void *args)
+{
+       void *data = heap->data;
+
+       if (WARN_ONCE(heap->nr <= 0, "Popping an empty heap"))
+               return false;
+
+       /* Place last element at the root (position 0) and then sift down. */
+       heap->nr--;
+       if (idx == heap->nr)
+               return true;
+       func->swp(data + (idx * elem_size), data + (heap->nr * elem_size), args);
+       __min_heap_sift_up(heap, elem_size, idx, func, args);
+       __min_heapify(heap, idx, elem_size, func, args);
+
+       return true;
+}
+
+#define min_heap_del(_heap, _idx, _func, _args)        \
+       __min_heap_del((min_heap_char *)_heap, __minheap_obj_size(_heap), _idx, _func, _args)
+
 #endif /* _LINUX_MIN_HEAP_H */