[PATCH 4.14 140/217] samples/bpf: Check the error of write() and read()

Greg Kroah-Hartman
2018-08-23T08:31:41Z

From: Taeung Song <treeze.taeung@gmail.com>

[ Upstream commit 02a2f000a3629274bfad60bfc4de9edec49e63e7 ]

test_task_rename() and test_urandom_read()
can be failed during write() and read(),
So check the result of them.

Reviewed-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
samples/bpf/test_overhead_user.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

--- a/samples/bpf/test_overhead_user.c
+++ b/samples/bpf/test_overhead_user.c
@@ -6,6 +6,7 @@
*/
#define _GNU_SOURCE
#include <sched.h>
+#include <errno.h>
#include <stdio.h>
#include <sys/types.h>
#include <asm/unistd.h>
@@ -44,8 +45,13 @@ static void test_task_rename(int cpu)
exit(1);
}
start_time = time_get_ns();
- for (i = 0; i < MAX_CNT; i++)
- write(fd, buf, sizeof(buf));
+ for (i = 0; i < MAX_CNT; i++) {
+ if (write(fd, buf, sizeof(buf)) < 0) {
+ printf("task rename failed: %s\n", strerror(errno));
+ close(fd);
+ return;
+ }
+ }
printf("task_rename:%d: %lld events per sec\n",
cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
close(fd);
@@ -63,8 +69,13 @@ static void test_urandom_read(int cpu)
exit(1);
}
start_time = time_get_ns();
- for (i = 0; i < MAX_CNT; i++)
- read(fd, buf, sizeof(buf));
+ for (i = 0; i < MAX_CNT; i++) {
+ if (read(fd, buf, sizeof(buf)) < 0) {
+ printf("failed to read from /dev/urandom: %s\n", strerror(errno));
+ close(fd);
+ return;
+ }
+ }
printf("urandom_read:%d: %lld events per sec\n",
cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
close(fd);