scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/samples/user_events/example.c b/samples/user_events/example.c
new file mode 100644
index 000000000..28165a096
--- /dev/null
+++ b/samples/user_events/example.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021, Microsoft Corporation.
+ *
+ * Authors:
+ *   Beau Belgrave <beaub@linux.microsoft.com>
+ */
+
+#include <errno.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/uio.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <linux/user_events.h>
+
+const char *data_file = "/sys/kernel/tracing/user_events_data";
+int enabled = 0;
+
+static int event_reg(int fd, const char *command, int *write, int *enabled)
+{
+	struct user_reg reg = {0};
+
+	reg.size = sizeof(reg);
+	reg.enable_bit = 31;
+	reg.enable_size = sizeof(*enabled);
+	reg.enable_addr = (__u64)enabled;
+	reg.name_args = (__u64)command;
+
+	if (ioctl(fd, DIAG_IOCSREG, &reg) == -1)
+		return -1;
+
+	*write = reg.write_index;
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int data_fd, write;
+	struct iovec io[2];
+	__u32 count = 0;
+
+	data_fd = open(data_file, O_RDWR);
+
+	if (event_reg(data_fd, "test u32 count", &write, &enabled) == -1)
+		return errno;
+
+	/* Setup iovec */
+	io[0].iov_base = &write;
+	io[0].iov_len = sizeof(write);
+	io[1].iov_base = &count;
+	io[1].iov_len = sizeof(count);
+ask:
+	printf("Press enter to check status...\n");
+	getchar();
+
+	/* Check if anyone is listening */
+	if (enabled) {
+		/* Yep, trace out our data */
+		writev(data_fd, (const struct iovec *)io, 2);
+
+		/* Increase the count */
+		count++;
+
+		printf("Something was attached, wrote data\n");
+	}
+
+	goto ask;
+
+	return 0;
+}