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Subject[PATCH v3] sched/rt: fix the case where sched_rt_period_us is negative
Date
The proc_dointvec() is for integer, but sysctl_sched_rt_period is a
unsigned integer, proc_dointvec() would convert negative number into
positive number. So both proc_dointvec() and sched_rt_global_validate()
aren't return error even if we set a negative number.

Use proc_dointvec_minmax() instead of proc_dointvec() and use extra1
limit the minimum value for sched_rt_period_us/sched_rt_runtime_us.

Make sysctl_sched_rt_period integer to match proc_dointvec_minmax().

v3:
- Make sysctl_sched_rt_period integer (Valentin Schneider)
v2:
- Remove sched_rr_timeslice_ms related changes (Valentin Schneider)

Fixes: d0b27fa77854 ("sched: rt-group: synchonised bandwidth period")
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
kernel/sched/rt.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 8c9ed9664840..cafc580edbe4 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -16,7 +16,7 @@ struct rt_bandwidth def_rt_bandwidth;
* period over which we measure -rt task CPU usage in us.
* default: 1s
*/
-unsigned int sysctl_sched_rt_period = 1000000;
+int sysctl_sched_rt_period = 1000000;

/*
* part of the period that we allow rt tasks to run in us.
@@ -34,9 +34,10 @@ static struct ctl_table sched_rt_sysctls[] = {
{
.procname = "sched_rt_period_us",
.data = &sysctl_sched_rt_period,
- .maxlen = sizeof(unsigned int),
+ .maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sched_rt_handler,
+ .extra1 = SYSCTL_ONE,
},
{
.procname = "sched_rt_runtime_us",
@@ -44,6 +45,7 @@ static struct ctl_table sched_rt_sysctls[] = {
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sched_rt_handler,
+ .extra1 = SYSCTL_NEG_ONE,
},
{
.procname = "sched_rr_timeslice_ms",
@@ -2960,9 +2962,6 @@ 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 *
@@ -2993,7 +2992,7 @@ 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();
--
2.25.1
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