dev->poll_limit_ns could be zeroed in certain cases (e.g. by
guest_halt_poll_ns = 0). If guest_halt_poll_grow_start is zero,
dev->poll_limit_ns will never be bigger than zero.
Use param callback to avoid writing zero to guest_halt_poll_grow_start.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
---
drivers/cpuidle/governors/haltpoll.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c
index 7a703d2..660859d 100644
--- a/drivers/cpuidle/governors/haltpoll.c
+++ b/drivers/cpuidle/governors/haltpoll.c
@@ -20,6 +20,26 @@
#include <linux/module.h>
#include <linux/kvm_para.h>
+static int grow_start_set(const char *val, const struct kernel_param *kp)
+{
+ int ret;
+ unsigned int n;
+
+ if (!val)
+ return -EINVAL;
+
+ ret = kstrtouint(val, 0, &n);
+ if (ret || !n)
+ return -EINVAL;
+
+ return param_set_uint(val, kp);
+}
+
+static const struct kernel_param_ops grow_start_ops = {
+ .set = grow_start_set,
+ .get = param_get_uint,
+};
+
static unsigned int guest_halt_poll_ns __read_mostly = 200000;
module_param(guest_halt_poll_ns, uint, 0644);
@@ -33,7 +53,7 @@
/* value in us to start growing per-cpu halt_poll_ns */
static unsigned int guest_halt_poll_grow_start __read_mostly = 50000;
-module_param(guest_halt_poll_grow_start, uint, 0644);
+module_param_cb(guest_halt_poll_grow_start, &grow_start_ops, &guest_halt_poll_grow_start, 0644);
/* allow shrinking guest halt poll */
static bool guest_halt_poll_allow_shrink __read_mostly = true;
--
1.8.3.1
