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| author | Liu Song <fishland@aliyun.com> | 2019-02-21 22:13:27 +0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-03-26 14:37:49 -0700 |
| commit | 3ffe3d1adc0b6cfb9b24db9995a537bb0aa30a8b (patch) | |
| tree | 73b20bcb0515f8bd86c092221415cfb2d2b2db1f /kernel/rcu | |
| parent | 884157cef0acf05648fe921d80c680afababb428 (diff) | |
| download | lwn-3ffe3d1adc0b6cfb9b24db9995a537bb0aa30a8b.tar.gz lwn-3ffe3d1adc0b6cfb9b24db9995a537bb0aa30a8b.zip | |
rcu: Set rcutree.kthread_prio sysfs access to read-only
The rcutree.kthread_prio kernel-boot parameter is used to set the
priority for boost (rcub), per-CPU (rcuc), and grace-period (rcu_preempt
or rcu_sched) kthreads. It is also used by rcutorture to check whether
it is possible to meaningfully test RCU priority boosting. However,
all of these cases will either ignore or be confused by any post-boot
changes to rcutree.kthread_prio.
Note that the user really can change the priorities of all of these
kthreads using chrt, given sufficient privileges. Therefore, the
read-write nature of sysfs access to rcutree.kthread_prio is thus at
best an attractive nuisance.
This commit therefore changes sysfs access to rcutree.kthread_prio to
be read-only.
Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 2f78a115d34c..296131450414 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -149,7 +149,7 @@ static void sync_sched_exp_online_cleanup(int cpu); /* rcuc/rcub kthread realtime priority */ static int kthread_prio = IS_ENABLED(CONFIG_RCU_BOOST) ? 1 : 0; -module_param(kthread_prio, int, 0644); +module_param(kthread_prio, int, 0444); /* Delay in jiffies for grace-period initialization delays, debug only. */ |