linux-kernel - [PATCH] sched/psi: create /proc/pressure and /proc/pressure/{io|memory|cpu} only when psi enabled

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Message-Id: <1576672698-32504-1-git-send-email-w@laoqinren.net>
Date:   Wed, 18 Dec 2019 20:38:18 +0800
From:   Wang Long <w@...qinren.net>
To:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de
Cc:     linux-kernel@...r.kernel.org, Wang Long <w@...qinren.net>
Subject: [PATCH] sched/psi: create /proc/pressure and /proc/pressure/{io|memory|cpu} only when psi enabled

when CONFIG_PSI_DEFAULT_DISABLED set to N or the command line set psi=0,
I think we should not create /proc/pressure and
/proc/pressure/{io|memory|cpu}.

In the future, user maybe determine whether the psi feature is enabled by
checking the existence of the /proc/pressure dir or
/proc/pressure/{io|memory|cpu} files.

Signed-off-by: Wang Long <w@...qinren.net>
---
 kernel/sched/psi.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 517e371..f12ade2 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1279,10 +1279,12 @@ static int psi_fop_release(struct inode *inode, struct file *file)
 
 static int __init psi_proc_init(void)
 {
-	proc_mkdir("pressure", NULL);
-	proc_create("pressure/io", 0, NULL, &psi_io_fops);
-	proc_create("pressure/memory", 0, NULL, &psi_memory_fops);
-	proc_create("pressure/cpu", 0, NULL, &psi_cpu_fops);
+	if (psi_enable) {
+		proc_mkdir("pressure", NULL);
+		proc_create("pressure/io", 0, NULL, &psi_io_fops);
+		proc_create("pressure/memory", 0, NULL, &psi_memory_fops);
+		proc_create("pressure/cpu", 0, NULL, &psi_cpu_fops);
+	}
 	return 0;
 }
 module_init(psi_proc_init);
-- 
1.8.3.1