linux-kernel - [PATCH] x86/resctrl: Constify kernfs

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Message-Id: <20201110230228.801785-1-rikard.falkeborn@gmail.com>
Date:   Wed, 11 Nov 2020 00:02:28 +0100
From:   Rikard Falkeborn <rikard.falkeborn@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Rikard Falkeborn <rikard.falkeborn@...il.com>
Subject: [PATCH] x86/resctrl: Constify kernfs_ops

The only usage of the kf_ops field in the rftype struct is to pass it as
argument to __kernfs_create_file(), which accepts a pointer to const.
Make it a pointer to const. This makes it possible to make
rdtgroup_kf_single_ops and kf_mondata_ops const, which allows the
compiler to put them in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@...il.com>
---
 arch/x86/kernel/cpu/resctrl/internal.h | 2 +-
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 6cb068fcf501..5540b025880c 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -264,7 +264,7 @@ void __exit rdtgroup_exit(void);
 struct rftype {
 	char			*name;
 	umode_t			mode;
-	struct kernfs_ops	*kf_ops;
+	const struct kernfs_ops	*kf_ops;
 	unsigned long		flags;
 	unsigned long		fflags;
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index af323e2e3100..78dcbb8e0172 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -240,13 +240,13 @@ static ssize_t rdtgroup_file_write(struct kernfs_open_file *of, char *buf,
 	return -EINVAL;
 }
 
-static struct kernfs_ops rdtgroup_kf_single_ops = {
+static const struct kernfs_ops rdtgroup_kf_single_ops = {
 	.atomic_write_len	= PAGE_SIZE,
 	.write			= rdtgroup_file_write,
 	.seq_show		= rdtgroup_seqfile_show,
 };
 
-static struct kernfs_ops kf_mondata_ops = {
+static const struct kernfs_ops kf_mondata_ops = {
 	.atomic_write_len	= PAGE_SIZE,
 	.seq_show		= rdtgroup_mondata_show,
 };
-- 
2.29.2