1 files changed, 53 insertions, 16 deletions

diff --git a/lib/sort.c b/lib/sort.c
index cf408aec3733..b399bf10d675 100644
--- a/lib/sort.c
+++ b/lib/sort.c
@@ -51,7 +51,7 @@ static bool is_aligned(const void *base, size_t size, unsigned char align)
  * which basically all CPUs have, to minimize loop overhead computations.
  *
  * For some reason, on x86 gcc 7.3.0 adds a redundant test of n at the
- * bottom of the loop, even though the zero flag is stil valid from the
+ * bottom of the loop, even though the zero flag is still valid from the
  * subtract (since the intervening mov instructions don't alter the flags).
  * Gcc 8.1.0 doesn't have that problem.
  */
@@ -117,23 +117,32 @@ static void swap_bytes(void *a, void *b, size_t n)
 	} while (n);
 }
 
-typedef void (*swap_func_t)(void *a, void *b, int size);
-
 /*
  * The values are arbitrary as long as they can't be confused with
  * a pointer, but small integers make for the smallest compare
  * instructions.
  */
-#define SWAP_WORDS_64 (swap_func_t)0
-#define SWAP_WORDS_32 (swap_func_t)1
-#define SWAP_BYTES    (swap_func_t)2
+#define SWAP_WORDS_64 (swap_r_func_t)0
+#define SWAP_WORDS_32 (swap_r_func_t)1
+#define SWAP_BYTES    (swap_r_func_t)2
+#define SWAP_WRAPPER  (swap_r_func_t)3
+
+struct wrapper {
+	cmp_func_t cmp;
+	swap_func_t swap;
+};
 
 /*
  * The function pointer is last to make tail calls most efficient if the
  * compiler decides not to inline this function.
  */
-static void do_swap(void *a, void *b, size_t size, swap_func_t swap_func)
+static void do_swap(void *a, void *b, size_t size, swap_r_func_t swap_func, const void *priv)
 {
+	if (swap_func == SWAP_WRAPPER) {
+		((const struct wrapper *)priv)->swap(a, b, (int)size);
+		return;
+	}
+
 	if (swap_func == SWAP_WORDS_64)
 		swap_words_64(a, b, size);
 	else if (swap_func == SWAP_WORDS_32)
@@ -141,7 +150,16 @@ static void do_swap(void *a, void *b, size_t size, swap_func_t swap_func)
 	else if (swap_func == SWAP_BYTES)
 		swap_bytes(a, b, size);
 	else
-		swap_func(a, b, (int)size);
+		swap_func(a, b, (int)size, priv);
+}
+
+#define _CMP_WRAPPER ((cmp_r_func_t)0L)
+
+static int do_cmp(const void *a, const void *b, cmp_r_func_t cmp, const void *priv)
+{
+	if (cmp == _CMP_WRAPPER)
+		return ((const struct wrapper *)priv)->cmp(a, b);
+	return cmp(a, b, priv);
 }
 
 /**
@@ -171,12 +189,13 @@ static size_t parent(size_t i, unsigned int lsbit, size_t size)
 }
 
 /**
- * sort - sort an array of elements
+ * sort_r - sort an array of elements
  * @base: pointer to data to sort
  * @num: number of elements
  * @size: size of each element
  * @cmp_func: pointer to comparison function
  * @swap_func: pointer to swap function or NULL
+ * @priv: third argument passed to comparison function
  *
  * This function does a heapsort on the given array.  You may provide
  * a swap_func function if you need to do something more than a memory
@@ -188,9 +207,10 @@ static size_t parent(size_t i, unsigned int lsbit, size_t size)
  * O(n*n) worst-case behavior and extra memory requirements that make
  * it less suitable for kernel use.
  */
-void sort(void *base, size_t num, size_t size,
-	  int (*cmp_func)(const void *, const void *),
-	  void (*swap_func)(void *, void *, int size))
+void sort_r(void *base, size_t num, size_t size,
+	    cmp_r_func_t cmp_func,
+	    swap_r_func_t swap_func,
+	    const void *priv)
 {
 	/* pre-scale counters for performance */
 	size_t n = num * size, a = (num/2) * size;
@@ -199,6 +219,10 @@ void sort(void *base, size_t num, size_t size,
 	if (!a)		/* num < 2 || size == 0 */
 		return;
 
+	/* called from 'sort' without swap function, let's pick the default */
+	if (swap_func == SWAP_WRAPPER && !((struct wrapper *)priv)->swap)
+		swap_func = NULL;
+
 	if (!swap_func) {
 		if (is_aligned(base, size, 8))
 			swap_func = SWAP_WORDS_64;
@@ -221,7 +245,7 @@ void sort(void *base, size_t num, size_t size,
 		if (a)			/* Building heap: sift down --a */
 			a -= size;
 		else if (n -= size)	/* Sorting: Extract root to --n */
-			do_swap(base, base + n, size, swap_func);
+			do_swap(base, base + n, size, swap_func, priv);
 		else			/* Sort complete */
 			break;
 
@@ -238,18 +262,31 @@ void sort(void *base, size_t num, size_t size,
 		 * average, 3/4 worst-case.)
 		 */
 		for (b = a; c = 2*b + size, (d = c + size) < n;)
-			b = cmp_func(base + c, base + d) >= 0 ? c : d;
+			b = do_cmp(base + c, base + d, cmp_func, priv) >= 0 ? c : d;
 		if (d == n)	/* Special case last leaf with no sibling */
 			b = c;
 
 		/* Now backtrack from "b" to the correct location for "a" */
-		while (b != a && cmp_func(base + a, base + b) >= 0)
+		while (b != a && do_cmp(base + a, base + b, cmp_func, priv) >= 0)
 			b = parent(b, lsbit, size);
 		c = b;			/* Where "a" belongs */
 		while (b != a) {	/* Shift it into place */
 			b = parent(b, lsbit, size);
-			do_swap(base + b, base + c, size, swap_func);
+			do_swap(base + b, base + c, size, swap_func, priv);
 		}
 	}
 }
+EXPORT_SYMBOL(sort_r);
+
+void sort(void *base, size_t num, size_t size,
+	  cmp_func_t cmp_func,
+	  swap_func_t swap_func)
+{
+	struct wrapper w = {
+		.cmp  = cmp_func,
+		.swap = swap_func,
+	};
+
+	return sort_r(base, num, size, _CMP_WRAPPER, SWAP_WRAPPER, &w);
+}
 EXPORT_SYMBOL(sort);