[LTP] [PATCH v2 2/3] lib: enhance .save_restore to support set expected value

[Li Wang <liwang@redhat.com>]

This extends that .save_restore support set new expected value after
saving the knob's original, which also avoids additionally checking
before using the file at other places.

And, export function tst_sys_conf_set() can be singly used for setting
new value of knob in the whole LTP.

Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
Suggested-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Li Wang <liwang@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
---

Notes:
    v1 --> v2
        * refine the description in doc as suggested by Cyril
        * remove redundant file check in tst_sys_conf_set
        * merge patch 3/4 into 2/4 for bisectability reason

 doc/c-test-api.txt                               | 14 ++++++++------
 include/tst_sys_conf.h                           |  6 ++++++
 include/tst_test.h                               |  2 +-
 lib/newlib_tests/test19.c                        | 14 ++++++--------
 lib/newlib_tests/test20.c                        | 10 ++++------
 lib/tst_sys_conf.c                               | 10 ++++++++++
 lib/tst_test.c                                   |  9 +++++----
 testcases/cve/icmp_rate_limit01.c                |  4 ++--
 testcases/kernel/containers/userns/userns08.c    |  4 ++--
 testcases/kernel/mem/ksm/ksm01.c                 |  4 ++--
 testcases/kernel/mem/ksm/ksm02.c                 |  4 ++--
 testcases/kernel/mem/ksm/ksm03.c                 |  4 ++--
 testcases/kernel/mem/ksm/ksm04.c                 |  4 ++--
 testcases/kernel/mem/ksm/ksm06.c                 | 10 +++++-----
 testcases/kernel/syscalls/add_key/add_key05.c    | 16 ++++------------
 testcases/kernel/syscalls/bind/bind06.c          |  4 ++--
 testcases/kernel/syscalls/madvise/madvise08.c    |  4 ++--
 .../syscalls/migrate_pages/migrate_pages02.c     |  5 ++---
 testcases/kernel/syscalls/sendto/sendto03.c      |  4 ++--
 .../kernel/syscalls/setsockopt/setsockopt05.c    |  4 ++--
 .../kernel/syscalls/setsockopt/setsockopt06.c    |  4 ++--
 .../kernel/syscalls/setsockopt/setsockopt07.c    |  4 ++--
 .../kernel/syscalls/setsockopt/setsockopt08.c    |  4 ++--
 .../kernel/syscalls/setsockopt/setsockopt09.c    |  4 ++--
 24 files changed, 79 insertions(+), 73 deletions(-)

diff --git a/doc/c-test-api.txt b/doc/c-test-api.txt
index 28383ccee..915255176 100644
--- a/doc/c-test-api.txt
+++ b/doc/c-test-api.txt
@@ -1561,10 +1561,12 @@ itself is not available on the system.
 
 LTP library can be instructed to save and restore value of specified
 (/proc|sys) files. This is achieved by initialized tst_test struct
-field 'save_restore'. It is a 'NULL' terminated array of strings where
-each string represents a file, whose value is saved at the beginning
-and restored at the end of the test. Only first line of a specified
-file is saved and restored.
+field 'save_restore'. It is a NULL-terminated array of struct
+'tst_path_val' where each tst_path_val.path represents a file, whose
+value is saved at the beginning and restored at the end of the test.
+If non-NULL value is passed it is written to the respective file at
+the beginning of the test. Only the first line of a specified file
+is saved and restored.
 
 Pathnames can be optionally prefixed to specify how strictly (during
 'store') are handled errors:
@@ -1578,8 +1580,8 @@ Pathnames can be optionally prefixed to specify how strictly (during
 
 [source,c]
 -------------------------------------------------------------------------------
-static const char *save_restore[] = {
-	"/proc/sys/kernel/core_pattern",
+static const struct tst_path_val save_restore[] = {
+	{"/proc/sys/kernel/core_pattern", NULL},
 	NULL,
 };
 
diff --git a/include/tst_sys_conf.h b/include/tst_sys_conf.h
index 507a552e8..b7bbe36fc 100644
--- a/include/tst_sys_conf.h
+++ b/include/tst_sys_conf.h
@@ -5,8 +5,14 @@
 #ifndef TST_SYS_CONF_H__
 #define TST_SYS_CONF_H__
 
+struct tst_path_val {
+        const char *path;
+        const char *val;
+};
+
 int tst_sys_conf_save_str(const char *path, const char *value);
 int tst_sys_conf_save(const char *path);
+void tst_sys_conf_set(const char *path, const char *value);
 void tst_sys_conf_restore(int verbose);
 void tst_sys_conf_dump(void);
 
diff --git a/include/tst_test.h b/include/tst_test.h
index 816fab4dd..e514efa76 100644
--- a/include/tst_test.h
+++ b/include/tst_test.h
@@ -259,7 +259,7 @@ struct tst_test {
 	 * NULL terminated array of (/proc, /sys) files to save
 	 * before setup and restore after cleanup
 	 */
-	const char * const *save_restore;
+	const struct tst_path_val const *save_restore;
 
 	/*
 	 * NULL terminated array of kernel config options required for the
diff --git a/lib/newlib_tests/test19.c b/lib/newlib_tests/test19.c
index 78b5202d2..402a2ad30 100644
--- a/lib/newlib_tests/test19.c
+++ b/lib/newlib_tests/test19.c
@@ -8,13 +8,6 @@
 #include "tst_test.h"
 #include "tst_sys_conf.h"
 
-static const char * const save_restore[] = {
-	"?/proc/nonexistent",
-	"!/proc/sys/kernel/numa_balancing",
-	"/proc/sys/kernel/core_pattern",
-	NULL,
-};
-
 static void setup(void)
 {
 	SAFE_FILE_PRINTF("/proc/sys/kernel/core_pattern", "changed");
@@ -30,5 +23,10 @@ static struct tst_test test = {
 	.needs_root = 1,
 	.test_all = run,
 	.setup = setup,
-	.save_restore = save_restore,
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/nonexistent", NULL},
+		{"!/proc/sys/kernel/numa_balancing", NULL},
+		{"/proc/sys/kernel/core_pattern", NULL},
+		NULL,
+	},
 };
diff --git a/lib/newlib_tests/test20.c b/lib/newlib_tests/test20.c
index 53317b669..5feb7c144 100644
--- a/lib/newlib_tests/test20.c
+++ b/lib/newlib_tests/test20.c
@@ -11,11 +11,6 @@
 #include "tst_hugepage.h"
 #include "tst_sys_conf.h"
 
-static const char * const save_restore[] = {
-	"!/proc/sys/kernel/numa_balancing",
-	NULL,
-};
-
 static void do_test(void) {
 
 	unsigned long val, hpages;
@@ -41,5 +36,8 @@ static void do_test(void) {
 static struct tst_test test = {
 	.test_all = do_test,
 	.request_hugepages = 2,
-	.save_restore = save_restore,
+	.save_restore = (const struct tst_path_val const[]) {
+		{"!/proc/sys/kernel/numa_balancing", "0"},
+		NULL,
+	},
 };
diff --git a/lib/tst_sys_conf.c b/lib/tst_sys_conf.c
index d7118f15f..003698825 100644
--- a/lib/tst_sys_conf.c
+++ b/lib/tst_sys_conf.c
@@ -96,6 +96,16 @@ int tst_sys_conf_save(const char *path)
 	return tst_sys_conf_save_str(path, line);
 }
 
+void tst_sys_conf_set(const char *path, const char *value)
+{
+	char flag = path[0];
+	if (flag  == '?' || flag == '!')
+		path++;
+
+	if (value)
+		SAFE_FILE_PRINTF(path, "%s", value);
+}
+
 void tst_sys_conf_restore(int verbose)
 {
 	struct tst_sys_conf *i;
diff --git a/lib/tst_test.c b/lib/tst_test.c
index 9e745c537..fe2e2bb6c 100644
--- a/lib/tst_test.c
+++ b/lib/tst_test.c
@@ -1105,11 +1105,12 @@ static void do_setup(int argc, char *argv[])
 		tst_tmpdir();
 
 	if (tst_test->save_restore) {
-		const char * const *name = tst_test->save_restore;
+		const struct tst_path_val const *pvl = tst_test->save_restore;
 
-		while (*name) {
-			tst_sys_conf_save(*name);
-			name++;
+		while (pvl->path) {
+			if (!tst_sys_conf_save(pvl->path))
+				tst_sys_conf_set(pvl->path, pvl->val);
+			pvl++;
 		}
 	}
 
diff --git a/testcases/cve/icmp_rate_limit01.c b/testcases/cve/icmp_rate_limit01.c
index 3ada32675..81735ce18 100644
--- a/testcases/cve/icmp_rate_limit01.c
+++ b/testcases/cve/icmp_rate_limit01.c
@@ -268,8 +268,8 @@ static struct tst_test test = {
 		"CONFIG_NET_NS=y",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
diff --git a/testcases/kernel/containers/userns/userns08.c b/testcases/kernel/containers/userns/userns08.c
index c141b1aca..33d0a9997 100644
--- a/testcases/kernel/containers/userns/userns08.c
+++ b/testcases/kernel/containers/userns/userns08.c
@@ -134,8 +134,8 @@ static struct tst_test test = {
 		"CONFIG_USER_NS",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
diff --git a/testcases/kernel/mem/ksm/ksm01.c b/testcases/kernel/mem/ksm/ksm01.c
index 7470d3143..0a81e2016 100644
--- a/testcases/kernel/mem/ksm/ksm01.c
+++ b/testcases/kernel/mem/ksm/ksm01.c
@@ -103,8 +103,8 @@ static struct tst_test test = {
 	},
 	.setup = setup,
 	.cleanup = cleanup,
-	.save_restore = (const char * const[]) {
-		"?/sys/kernel/mm/ksm/max_page_sharing",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/sys/kernel/mm/ksm/max_page_sharing", NULL},
 		NULL,
 	},
 	.test_all = verify_ksm,
diff --git a/testcases/kernel/mem/ksm/ksm02.c b/testcases/kernel/mem/ksm/ksm02.c
index 76a87c6b1..6ba6ee868 100644
--- a/testcases/kernel/mem/ksm/ksm02.c
+++ b/testcases/kernel/mem/ksm/ksm02.c
@@ -115,8 +115,8 @@ static struct tst_test test = {
 	},
 	.setup = setup,
 	.cleanup = cleanup,
-	.save_restore = (const char * const[]) {
-		"?/sys/kernel/mm/ksm/max_page_sharing",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/sys/kernel/mm/ksm/max_page_sharing", NULL},
 		NULL,
 	},
 	.test_all = verify_ksm,
diff --git a/testcases/kernel/mem/ksm/ksm03.c b/testcases/kernel/mem/ksm/ksm03.c
index 6a0566f43..71d2d8bd9 100644
--- a/testcases/kernel/mem/ksm/ksm03.c
+++ b/testcases/kernel/mem/ksm/ksm03.c
@@ -100,8 +100,8 @@ static struct tst_test test = {
 	},
 	.setup = setup,
 	.cleanup = cleanup,
-	.save_restore = (const char * const[]) {
-		"?/sys/kernel/mm/ksm/max_page_sharing",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/sys/kernel/mm/ksm/max_page_sharing", NULL},
 		NULL,
 	},
 	.test_all = verify_ksm,
diff --git a/testcases/kernel/mem/ksm/ksm04.c b/testcases/kernel/mem/ksm/ksm04.c
index 77fafa641..8429f4843 100644
--- a/testcases/kernel/mem/ksm/ksm04.c
+++ b/testcases/kernel/mem/ksm/ksm04.c
@@ -116,8 +116,8 @@ static struct tst_test test = {
 	},
 	.setup = setup,
 	.cleanup = cleanup,
-	.save_restore = (const char * const[]) {
-		"?/sys/kernel/mm/ksm/max_page_sharing",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/sys/kernel/mm/ksm/max_page_sharing", NULL},
 		NULL,
 	},
 	.test_all = verify_ksm,
diff --git a/testcases/kernel/mem/ksm/ksm06.c b/testcases/kernel/mem/ksm/ksm06.c
index 6a74b7406..f28383cc0 100644
--- a/testcases/kernel/mem/ksm/ksm06.c
+++ b/testcases/kernel/mem/ksm/ksm06.c
@@ -136,11 +136,11 @@ static struct tst_test test = {
 		{}
 	},
 	.setup = setup,
-	.save_restore = (const char * const[]) {
-		"?/sys/kernel/mm/ksm/max_page_sharing",
-		"!/sys/kernel/mm/ksm/run",
-		"!/sys/kernel/mm/ksm/sleep_millisecs",
-		"/sys/kernel/mm/ksm/merge_across_nodes",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/sys/kernel/mm/ksm/max_page_sharing", NULL},
+		{"!/sys/kernel/mm/ksm/run", NULL},
+		{"!/sys/kernel/mm/ksm/sleep_millisecs", NULL},
+		{"/sys/kernel/mm/ksm/merge_across_nodes", NULL},
 		NULL,
 	},
 	.needs_kconfigs = (const char *const[]){
diff --git a/testcases/kernel/syscalls/add_key/add_key05.c b/testcases/kernel/syscalls/add_key/add_key05.c
index 2be1b7014..bbe44e043 100644
--- a/testcases/kernel/syscalls/add_key/add_key05.c
+++ b/testcases/kernel/syscalls/add_key/add_key05.c
@@ -202,13 +202,6 @@ static void do_test(unsigned int n)
 	return;
 }
 
-static void setup(void)
-{
-	SAFE_FILE_PRINTF("/proc/sys/kernel/keys/gc_delay", "1");
-	SAFE_FILE_PRINTF("/proc/sys/kernel/keys/maxkeys", "200");
-	SAFE_FILE_PRINTF("/proc/sys/kernel/keys/maxbytes", "20000");
-}
-
 static void cleanup(void)
 {
 	while (usern--)
@@ -220,12 +213,11 @@ static struct tst_test test = {
 	.tcnt = 2,
 	.needs_root = 1,
 	.forks_child = 1,
-	.setup = setup,
 	.cleanup = cleanup,
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/kernel/keys/gc_delay",
-		"?/proc/sys/kernel/keys/maxkeys",
-		"?/proc/sys/kernel/keys/maxbytes",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/kernel/keys/gc_delay", "1"},
+		{"?/proc/sys/kernel/keys/maxkeys", "200"},
+		{"?/proc/sys/kernel/keys/maxbytes", "20000"},
 		NULL,
 	},
 	.bufs = (struct tst_buffers []) {
diff --git a/testcases/kernel/syscalls/bind/bind06.c b/testcases/kernel/syscalls/bind/bind06.c
index 297311c04..7a84b19cd 100644
--- a/testcases/kernel/syscalls/bind/bind06.c
+++ b/testcases/kernel/syscalls/bind/bind06.c
@@ -109,8 +109,8 @@ static struct tst_test test = {
 		"CONFIG_NET_NS=y",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
diff --git a/testcases/kernel/syscalls/madvise/madvise08.c b/testcases/kernel/syscalls/madvise/madvise08.c
index ff167dafe..e513d558a 100644
--- a/testcases/kernel/syscalls/madvise/madvise08.c
+++ b/testcases/kernel/syscalls/madvise/madvise08.c
@@ -213,8 +213,8 @@ static struct tst_test test = {
 	.needs_tmpdir = 1,
 	.needs_root = 1,
 	.forks_child = 1,
-	.save_restore = (const char * const[]) {
-		CORE_PATTERN,
+	.save_restore = (const struct tst_path_val const[]) {
+		{CORE_PATTERN, NULL},
 		NULL,
 	},
 };
diff --git a/testcases/kernel/syscalls/migrate_pages/migrate_pages02.c b/testcases/kernel/syscalls/migrate_pages/migrate_pages02.c
index 485a1c5aa..162ff09a9 100644
--- a/testcases/kernel/syscalls/migrate_pages/migrate_pages02.c
+++ b/testcases/kernel/syscalls/migrate_pages/migrate_pages02.c
@@ -276,7 +276,6 @@ static void setup(void)
 	else if (tst_kvercmp(2, 6, 18) < 0)
 		tst_brk(TCONF, "2.6.18 or greater kernel required");
 
-	FILE_PRINTF("/proc/sys/kernel/numa_balancing", "0");
 	/*
 	 * find 2 nodes, which can hold NODE_MIN_FREEMEM bytes
 	 * The reason is that:
@@ -327,8 +326,8 @@ static struct tst_test test = {
 	.forks_child = 1,
 	.test_all = run,
 	.setup = setup,
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/kernel/numa_balancing",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/kernel/numa_balancing", "0"},
 		NULL,
 	},
 };
diff --git a/testcases/kernel/syscalls/sendto/sendto03.c b/testcases/kernel/syscalls/sendto/sendto03.c
index 217383993..4459f8849 100644
--- a/testcases/kernel/syscalls/sendto/sendto03.c
+++ b/testcases/kernel/syscalls/sendto/sendto03.c
@@ -217,8 +217,8 @@ static struct tst_test test = {
 		"CONFIG_NET_NS=y",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
diff --git a/testcases/kernel/syscalls/setsockopt/setsockopt05.c b/testcases/kernel/syscalls/setsockopt/setsockopt05.c
index 4b8b3d22e..abc76627a 100644
--- a/testcases/kernel/syscalls/setsockopt/setsockopt05.c
+++ b/testcases/kernel/syscalls/setsockopt/setsockopt05.c
@@ -101,8 +101,8 @@ static struct tst_test test = {
 		"CONFIG_NET_NS=y",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
diff --git a/testcases/kernel/syscalls/setsockopt/setsockopt06.c b/testcases/kernel/syscalls/setsockopt/setsockopt06.c
index 644e61f3f..25dd04a15 100644
--- a/testcases/kernel/syscalls/setsockopt/setsockopt06.c
+++ b/testcases/kernel/syscalls/setsockopt/setsockopt06.c
@@ -129,8 +129,8 @@ static struct tst_test test = {
 		"CONFIG_NET_NS=y",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
diff --git a/testcases/kernel/syscalls/setsockopt/setsockopt07.c b/testcases/kernel/syscalls/setsockopt/setsockopt07.c
index 7385ce79e..b405c8ece 100644
--- a/testcases/kernel/syscalls/setsockopt/setsockopt07.c
+++ b/testcases/kernel/syscalls/setsockopt/setsockopt07.c
@@ -141,8 +141,8 @@ static struct tst_test test = {
 		"CONFIG_NET_NS=y",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
diff --git a/testcases/kernel/syscalls/setsockopt/setsockopt08.c b/testcases/kernel/syscalls/setsockopt/setsockopt08.c
index 5b648d754..49eb17b13 100644
--- a/testcases/kernel/syscalls/setsockopt/setsockopt08.c
+++ b/testcases/kernel/syscalls/setsockopt/setsockopt08.c
@@ -158,8 +158,8 @@ static struct tst_test test = {
 		"CONFIG_NET_NS=y",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
diff --git a/testcases/kernel/syscalls/setsockopt/setsockopt09.c b/testcases/kernel/syscalls/setsockopt/setsockopt09.c
index 2fc66ebbc..53944247f 100644
--- a/testcases/kernel/syscalls/setsockopt/setsockopt09.c
+++ b/testcases/kernel/syscalls/setsockopt/setsockopt09.c
@@ -105,8 +105,8 @@ static struct tst_test test = {
 		"CONFIG_NET_NS=y",
 		NULL
 	},
-	.save_restore = (const char * const[]) {
-		"?/proc/sys/user/max_user_namespaces",
+	.save_restore = (const struct tst_path_val const[]) {
+		{"?/proc/sys/user/max_user_namespaces", NULL},
 		NULL,
 	},
 	.tags = (const struct tst_tag[]) {
-- 
2.31.1


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