watchdog: Disallow setting watchdog_thresh to -1

In old kernels, it's allowed to set softlockup_thresh to -1 or 0
to disable softlockup detection. However watchdog_thresh only
uses 0 to disable detection, and setting it to -1 just froze my
box and nothing I can do but reboot.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/51959668.9040106@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9edcf45..b0a1f99 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -120,7 +120,6 @@ extern int blk_iopoll_enabled;
 /* Constants used for minimum and  maximum */
 #ifdef CONFIG_LOCKUP_DETECTOR
 static int sixty = 60;
-static int neg_one = -1;
 #endif
 
 static int zero;
@@ -814,7 +813,7 @@ static struct ctl_table kern_table[] = {
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dowatchdog,
-               .extra1         = &neg_one,
+               .extra1         = &zero,
                .extra2         = &sixty,
        },
        {