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From:   Rong Tao <rtoax@foxmail.com>
To:     sj@kernel.org
Cc:     Rong Tao <rongtao@cestc.cn>, Shuah Khan <shuah@kernel.org>,
        damon@lists.linux.dev (open list:DATA ACCESS MONITOR),
        linux-mm@kvack.org (open list:DATA ACCESS MONITOR),
        linux-kselftest@vger.kernel.org (open list:KERNEL SELFTEST FRAMEWORK),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] selftests/damon: Fix unnecessary compilation warnings
Date:   Thu, 10 Nov 2022 21:34:18 +0800
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From: Rong Tao <rongtao@cestc.cn>

When testing overflow and overread, there is no need to keep unnecessary
compilation warnings, we should simply ignore them.

How to reproduce the problem:

$ make -C tools/testing/selftests/
gcc     huge_count_read_write.c  -o /home/sd/Git/linux/tools/testing/selftests/damon/huge_count_read_write
huge_count_read_write.c: In function ‘write_read_with_huge_count’:
huge_count_read_write.c:23:9: warning: ‘write’ reading 4294967295 bytes from a region of size 1 [-Wstringop-overread]
   23 |         write(filedesc, "", 0xfffffffful);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from huge_count_read_write.c:8:
/usr/include/unistd.h:378:16: note: in a call to function ‘write’ declared with attribute ‘access (read_only, 2, 3)’
  378 | extern ssize_t write (int __fd, const void *__buf, size_t __n) __wur
      |                ^~~~~
huge_count_read_write.c:25:15: warning: ‘read’ writing 4294967295 bytes into a region of size 25 overflows the destination [-Wstringop-overflow=]
   25 |         ret = read(filedesc, buf, 0xfffffffful);
      |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
huge_count_read_write.c:14:14: note: destination object ‘buf’ of size 25
   14 |         char buf[25];
      |              ^~~
In file included from huge_count_read_write.c:8:
/usr/include/unistd.h:371:16: note: in a call to function ‘read’ declared with attribute ‘access (write_only, 2, 3)’
  371 | extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __wur
      |                ^~~~

Signed-off-by: Rong Tao <rongtao@cestc.cn>
---
 tools/testing/selftests/damon/huge_count_read_write.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
index ad7a6b4cf338..8fbe276870e7 100644
--- a/tools/testing/selftests/damon/huge_count_read_write.c
+++ b/tools/testing/selftests/damon/huge_count_read_write.c
@@ -8,6 +8,11 @@
 #include <unistd.h>
 #include <stdio.h>
 
+#pragma GCC diagnostic push
+/* Ignore read(2) overflow and write(2) overread compile warnings */
+#pragma GCC diagnostic ignored "-Wstringop-overread"
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
+
 void write_read_with_huge_count(char *file)
 {
 	int filedesc = open(file, O_RDWR);
@@ -27,6 +32,8 @@ void write_read_with_huge_count(char *file)
 	close(filedesc);
 }
 
+#pragma GCC diagnostic pop
+
 int main(int argc, char *argv[])
 {
 	if (argc != 2) {
-- 
2.31.1