[PATCH] sched/rt: fix the case where sched_rt_period_us is non-positive

Yajun Deng
2022-05-11T11:22:40Z

The proc_dointvec() in sched_rt_handler() is for integer, but
sysctl_sched_rt_period is a unsigned integer. sched_rt_handler() would
cover a non-positive number to positive number, so both proc_dointvec()
and sched_rt_global_validate() aren't return error when we set a
non-positive number.

Use proc_dointvec_minmax() instead of proc_dointvec(), and add extra
for sched_rt_period_us/sched_rt_runtime_us/sched_rr_timeslice_ms.

Fixes: 391e43da797a ("sched: Move all scheduler bits into kernel/sched/")
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
kernel/sched/rt.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index b491a0f8c25d..f20389aa6731 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -37,6 +37,7 @@ static struct ctl_table sched_rt_sysctls[] = {
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = sched_rt_handler,
+ .extra1 = SYSCTL_ONE,
},
{
.procname = "sched_rt_runtime_us",
@@ -44,6 +45,8 @@ static struct ctl_table sched_rt_sysctls[] = {
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sched_rt_handler,
+ .extra1 = SYSCTL_NEG_ONE,
+ .extra2 = (void *)&sysctl_sched_rt_period,
},
{
.procname = "sched_rr_timeslice_ms",
@@ -51,6 +54,7 @@ static struct ctl_table sched_rt_sysctls[] = {
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sched_rr_handler,
+ .extra1 = SYSCTL_ONE,
},
{}
};
@@ -2959,9 +2963,6 @@ static int sched_rt_global_constraints(void)
#ifdef CONFIG_SYSCTL
static int sched_rt_global_validate(void)
{
- if (sysctl_sched_rt_period <= 0)
- return -EINVAL;
-
if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
((sysctl_sched_rt_runtime > sysctl_sched_rt_period) ||
((u64)sysctl_sched_rt_runtime *
@@ -2992,7 +2993,7 @@ static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
old_period = sysctl_sched_rt_period;
old_runtime = sysctl_sched_rt_runtime;

- ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);

if (!ret && write) {
ret = sched_rt_global_validate();
@@ -3027,14 +3028,13 @@ static int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
static DEFINE_MUTEX(mutex);

mutex_lock(&mutex);
- ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
/*
* Make sure that internally we keep jiffies.
* Also, writing zero resets the timeslice to default:
*/
if (!ret && write) {
sched_rr_timeslice =
- sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
msecs_to_jiffies(sysctl_sched_rr_timeslice);
}
mutex_unlock(&mutex);
--
2.25.1