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

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Message-ID: <157925572102.396.13781861787054630755.tip-bot2@tip-bot2>
Date:   Fri, 17 Jan 2020 10:08:41 -0000
From:   "tip-bot2 for Wang Long" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Wang Long <w@...qinren.net>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Johannes Weiner <hannes@...xchg.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: sched/core] sched/psi: create /proc/pressure and
 /proc/pressure/{io|memory|cpu} only when psi enabled

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     3d817689a62cf71bbb290af18cd26cf9764f38fe
Gitweb:        https://git.kernel.org/tip/3d817689a62cf71bbb290af18cd26cf9764f38fe
Author:        Wang Long <w@...qinren.net>
AuthorDate:    Wed, 18 Dec 2019 20:38:18 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 17 Jan 2020 10:19:22 +01:00

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Johannes Weiner <hannes@...xchg.org>
Link: https://lkml.kernel.org/r/1576672698-32504-1-git-send-email-w@laoqinren.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 ce8f674..db7b50b 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1280,10 +1280,12 @@ static const struct file_operations psi_cpu_fops = {
 
 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);