v4.19.13 snapshot.
diff --git a/lib/raid6/test/test.c b/lib/raid6/test/test.c
new file mode 100644
index 0000000..b07f4d8
--- /dev/null
+++ b/lib/raid6/test/test.c
@@ -0,0 +1,156 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ * Copyright 2002-2007 H. Peter Anvin - All Rights Reserved
+ *
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2 or (at your
+ * option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * raid6test.c
+ *
+ * Test RAID-6 recovery with various algorithms
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <linux/raid/pq.h>
+
+#define NDISKS 16 /* Including P and Q */
+
+const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+struct raid6_calls raid6_call;
+
+char *dataptrs[NDISKS];
+char data[NDISKS][PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+char recovi[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+char recovj[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+
+static void makedata(int start, int stop)
+{
+ int i, j;
+
+ for (i = start; i <= stop; i++) {
+ for (j = 0; j < PAGE_SIZE; j++)
+ data[i][j] = rand();
+
+ dataptrs[i] = data[i];
+ }
+}
+
+static char disk_type(int d)
+{
+ switch (d) {
+ case NDISKS-2:
+ return 'P';
+ case NDISKS-1:
+ return 'Q';
+ default:
+ return 'D';
+ }
+}
+
+static int test_disks(int i, int j)
+{
+ int erra, errb;
+
+ memset(recovi, 0xf0, PAGE_SIZE);
+ memset(recovj, 0xba, PAGE_SIZE);
+
+ dataptrs[i] = recovi;
+ dataptrs[j] = recovj;
+
+ raid6_dual_recov(NDISKS, PAGE_SIZE, i, j, (void **)&dataptrs);
+
+ erra = memcmp(data[i], recovi, PAGE_SIZE);
+ errb = memcmp(data[j], recovj, PAGE_SIZE);
+
+ if (i < NDISKS-2 && j == NDISKS-1) {
+ /* We don't implement the DQ failure scenario, since it's
+ equivalent to a RAID-5 failure (XOR, then recompute Q) */
+ erra = errb = 0;
+ } else {
+ printf("algo=%-8s faila=%3d(%c) failb=%3d(%c) %s\n",
+ raid6_call.name,
+ i, disk_type(i),
+ j, disk_type(j),
+ (!erra && !errb) ? "OK" :
+ !erra ? "ERRB" :
+ !errb ? "ERRA" : "ERRAB");
+ }
+
+ dataptrs[i] = data[i];
+ dataptrs[j] = data[j];
+
+ return erra || errb;
+}
+
+int main(int argc, char *argv[])
+{
+ const struct raid6_calls *const *algo;
+ const struct raid6_recov_calls *const *ra;
+ int i, j, p1, p2;
+ int err = 0;
+
+ makedata(0, NDISKS-1);
+
+ for (ra = raid6_recov_algos; *ra; ra++) {
+ if ((*ra)->valid && !(*ra)->valid())
+ continue;
+
+ raid6_2data_recov = (*ra)->data2;
+ raid6_datap_recov = (*ra)->datap;
+
+ printf("using recovery %s\n", (*ra)->name);
+
+ for (algo = raid6_algos; *algo; algo++) {
+ if ((*algo)->valid && !(*algo)->valid())
+ continue;
+
+ raid6_call = **algo;
+
+ /* Nuke syndromes */
+ memset(data[NDISKS-2], 0xee, 2*PAGE_SIZE);
+
+ /* Generate assumed good syndrome */
+ raid6_call.gen_syndrome(NDISKS, PAGE_SIZE,
+ (void **)&dataptrs);
+
+ for (i = 0; i < NDISKS-1; i++)
+ for (j = i+1; j < NDISKS; j++)
+ err += test_disks(i, j);
+
+ if (!raid6_call.xor_syndrome)
+ continue;
+
+ for (p1 = 0; p1 < NDISKS-2; p1++)
+ for (p2 = p1; p2 < NDISKS-2; p2++) {
+
+ /* Simulate rmw run */
+ raid6_call.xor_syndrome(NDISKS, p1, p2, PAGE_SIZE,
+ (void **)&dataptrs);
+ makedata(p1, p2);
+ raid6_call.xor_syndrome(NDISKS, p1, p2, PAGE_SIZE,
+ (void **)&dataptrs);
+
+ for (i = 0; i < NDISKS-1; i++)
+ for (j = i+1; j < NDISKS; j++)
+ err += test_disks(i, j);
+ }
+
+ }
+ printf("\n");
+ }
+
+ printf("\n");
+ /* Pick the best algorithm test */
+ raid6_select_algo();
+
+ if (err)
+ printf("\n*** ERRORS FOUND ***\n");
+
+ return err;
+}