[LTP] [PATCH v2] madvise11.c:Check loadable module before rmmod

[Wei Gao]

Following fail msg will popup if we try to rmmod buildin module:
rmmod: ERROR: Module hwpoison_inject is builtin

Before rmmod we should check this module can be rmmod or not.
Every modules which can show in lsmod output, it means the module can be unload.

But for output of /proc/modules i am not sure it can contain ONLY loadable module.

Signed-off-by: Wei Gao <wegao@suse.com>
---
 testcases/kernel/syscalls/madvise/madvise11.c | 32 +++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/testcases/kernel/syscalls/madvise/madvise11.c b/testcases/kernel/syscalls/madvise/madvise11.c
index 7e291d571..bac077fc8 100644
--- a/testcases/kernel/syscalls/madvise/madvise11.c
+++ b/testcases/kernel/syscalls/madvise/madvise11.c
@@ -33,6 +33,7 @@
 #define NUM_LOOPS	5
 #define NUM_PAGES	32
 #define NUM_PAGES_OFFSET	5
+#define MAX_BUF 4094
 
 /* Needed module to online back memory pages */
 #define HW_MODULE	"hwpoison_inject"
@@ -291,6 +292,31 @@ static void unpoison_this_pfn(unsigned long pfn, int fd)
 	SAFE_WRITE(0, fd, pfn_str, strlen(pfn_str));
 }
 
+static int is_loadable_module(const char *modname)
+{
+	char command[MAX_BUF];
+	char line[MAX_BUF];
+	char *token;
+
+	sprintf(command, "lsmod | grep '^%s'", modname);
+
+	FILE *fp = popen(command, "r");
+
+	if (fp == NULL)
+		tst_brk(TBROK, "Popen command %s failed", command);
+
+	if (fgets(line, MAX_BUF, fp) != NULL) {
+		token = strtok(line, " \t\n");
+		if (strcmp(token, modname) == 0) {
+			pclose(fp);
+			return 1;
+		}
+	}
+
+	pclose(fp);
+	return 0;
+}
+
 /* Find and open the <debugfs>/hwpoison/unpoison-pfn special file */
 static int open_unpoison_pfn(void)
 {
@@ -337,6 +363,7 @@ static void unpoison_pfn(char *begin_tag)
 	unsigned long *pfns;
 	const char *const cmd_rmmod[] = {"rmmod", HW_MODULE, NULL};
 	int found_pfns, fd;
+	int is_loadable = -1;
 
 	pfns = SAFE_MALLOC(sizeof(pfns) * maximum_pfns * run_iterations);
 
@@ -351,8 +378,9 @@ static void unpoison_pfn(char *begin_tag)
 
 		SAFE_CLOSE(fd);
 	}
-	/* remove hwpoison only if we probed it */
-	if (hwpoison_probe)
+	/* remove hwpoison only if we probed it and not built in*/
+	is_loadable = is_loadable_module(HW_MODULE);
+	if (hwpoison_probe && (is_loadable == 1))
 		SAFE_CMD(cmd_rmmod, NULL, NULL);
 }
 
-- 
2.35.3