linux-kernel - [PATCH] x86/platform/uv: Use sysfs_match_string() for string parsing in param_set

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Date:   Wed, 13 Sep 2023 17:16:56 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Steve Wahl <steve.wahl@....com>,
        Justin Ernst <justin.ernst@....com>,
        Kyle Meyer <kyle.meyer@....com>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Russ Anderson <russ.anderson@....com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H . Peter Anvin" <hpa@...or.com>
Cc:     Hans de Goede <hdegoede@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] x86/platform/uv: Use sysfs_match_string() for string parsing in param_set_action()

Remove the custom, hard to read code to:

1. Make a copy of "val" with any potential '\n' at the end stripped
2. Compare the copy against an array of allowed string values

Linux has the sysfs_match_string() helper exactly for cases like this,
switch to this.

Cc: Justin Stitt <justinstitt@...gle.com>
Signed-off-by: Hans de Goede <hdegoede@...hat.com>
---
 arch/x86/platform/uv/uv_nmi.c | 48 +++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 22 deletions(-)

diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
index 45d0c17ce77c..44bacb547c65 100644
--- a/arch/x86/platform/uv/uv_nmi.c
+++ b/arch/x86/platform/uv/uv_nmi.c
@@ -179,17 +179,27 @@ module_param_named(debug, uv_nmi_debug, int, 0644);
 
 /* Valid NMI Actions */
 #define	ACTION_LEN	16
-static struct nmi_action {
-	char	*action;
-	char	*desc;
-} valid_acts[] = {
-	{	"kdump",	"do kernel crash dump"			},
-	{	"dump",		"dump process stack for each cpu"	},
-	{	"ips",		"dump Inst Ptr info for each cpu"	},
-	{	"kdb",		"enter KDB (needs kgdboc= assignment)"	},
-	{	"kgdb",		"enter KGDB (needs gdb target remote)"	},
-	{	"health",	"check if CPUs respond to NMI"		},
+
+static const char * const valid_acts[] = {
+	"kdump",
+	"dump",
+	"ips",
+	"kdb",
+	"kgdb",
+	"health",
 };
+
+static const char * const valid_acts_desc[] = {
+	"do kernel crash dump",
+	"dump process stack for each cpu",
+	"dump Inst Ptr info for each cpu",
+	"enter KDB (needs kgdboc= assignment)",
+	"enter KGDB (needs gdb target remote)",
+	"check if CPUs respond to NMI",
+};
+
+static_assert(ARRAY_SIZE(valid_acts) == ARRAY_SIZE(valid_acts_desc));
+
 typedef char action_t[ACTION_LEN];
 static action_t uv_nmi_action = { "dump" };
 
@@ -202,25 +212,19 @@ static int param_set_action(const char *val, const struct kernel_param *kp)
 {
 	int i;
 	int n = ARRAY_SIZE(valid_acts);
-	char arg[ACTION_LEN];
 
-	/* (remove possible '\n') */
-	strscpy(arg, val, strnchrnul(val, sizeof(arg)-1, '\n') - val + 1);
+	i = sysfs_match_string(valid_acts, val);
 
-	for (i = 0; i < n; i++)
-		if (!strcmp(arg, valid_acts[i].action))
-			break;
-
-	if (i < n) {
-		strscpy(uv_nmi_action, arg, sizeof(uv_nmi_action));
+	if (i >= 0) {
+		strscpy(uv_nmi_action, valid_acts[i], sizeof(uv_nmi_action));
 		pr_info("UV: New NMI action:%s\n", uv_nmi_action);
 		return 0;
 	}
 
-	pr_err("UV: Invalid NMI action:%s, valid actions are:\n", arg);
+	pr_err("UV: Invalid NMI action:%s, valid actions are:\n", val);
 	for (i = 0; i < n; i++)
-		pr_err("UV: %-8s - %s\n",
-			valid_acts[i].action, valid_acts[i].desc);
+		pr_err("UV: %-8s - %s\n", valid_acts[i], valid_acts_desc[i]);
+
 	return -EINVAL;
 }
 
-- 
2.41.0