[S390] vdso: kernel parameter syntax

The syntax of the vdso kernel parameter is documented as vdso=[on|off].
The implementation uses vdso=[0|1], an invalid parameter string disables
the vdso support. Fix the mismatch by adding vdso=[on|off] as additional
parameter syntax.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 89b2e7f1b7a9..7b76ee4fb16c 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -53,8 +53,19 @@ unsigned int __read_mostly vdso_enabled = 1;
 
 static int __init vdso_setup(char *s)
 {
-        vdso_enabled = simple_strtoul(s, NULL, 0);
-        return 1;
+        unsigned long val;
+        int rc;
+
+        rc = 0;
+        if (strncmp(s, "on", 3) == 0)
+                vdso_enabled = 1;
+        else if (strncmp(s, "off", 4) == 0)
+                vdso_enabled = 0;
+        else {
+                rc = strict_strtoul(s, 0, &val);
+                vdso_enabled = rc ? 0 : !!val;
+        }
+        return !rc;
 }
 __setup("vdso=", vdso_setup);