linux-kernel - [PATCH] map.c: refactoring magic constant

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Date: Wed, 24 Apr 2024 14:25:33 +0200
From: Andrea Calabrese <andrea.calabrese@...rulasolutions.com>
To: linux-kernel@...r.kernel.org
Cc: trivial@...nel.org,
	Andrea Calabrese <andrea.calabrese@...rulasolutions.com>
Subject: [PATCH] map.c: refactoring magic constant

In map.c there is a magic constant of value 255 for the maximum number
of probes. It is in many places in the code, in this commit I modified
it to make it more clear

Signed-off-by: Andrea Calabrese <andrea.calabrese@...rulasolutions.com>
---
 drivers/base/map.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/base/map.c b/drivers/base/map.c
index 83aeb09ca161..b27f0cf557f4 100644
--- a/drivers/base/map.c
+++ b/drivers/base/map.c
@@ -16,6 +16,8 @@
 #include <linux/kobject.h>
 #include <linux/kobj_map.h>
 
+#define MAX_PROBES = 255
+
 struct kobj_map {
 	struct probe {
 		struct probe *next;
@@ -25,7 +27,7 @@ struct kobj_map {
 		kobj_probe_t *get;
 		int (*lock)(dev_t, void *);
 		void *data;
-	} *probes[255];
+	} *probes[MAX_PROBES];
 	struct mutex *lock;
 };
 
@@ -38,8 +40,8 @@ int kobj_map(struct kobj_map *domain, dev_t dev, unsigned long range,
 	unsigned int i;
 	struct probe *p;
 
-	if (n > 255)
-		n = 255;
+	if (n > MAX_PROBES)
+		n = MAX_PROBES;
 
 	p = kmalloc_array(n, sizeof(struct probe), GFP_KERNEL);
 	if (p == NULL)
@@ -55,7 +57,7 @@ int kobj_map(struct kobj_map *domain, dev_t dev, unsigned long range,
 	}
 	mutex_lock(domain->lock);
 	for (i = 0, p -= n; i < n; i++, p++, index++) {
-		struct probe **s = &domain->probes[index % 255];
+		struct probe **s = &domain->probes[index % MAX_PROBES];
 		while (*s && (*s)->range < range)
 			s = &(*s)->next;
 		p->next = *s;
@@ -72,13 +74,13 @@ void kobj_unmap(struct kobj_map *domain, dev_t dev, unsigned long range)
 	unsigned int i;
 	struct probe *found = NULL;
 
-	if (n > 255)
-		n = 255;
+	if (n > MAX_PROBES)
+		n = MAX_PROBES;
 
 	mutex_lock(domain->lock);
 	for (i = 0; i < n; i++, index++) {
 		struct probe **s;
-		for (s = &domain->probes[index % 255]; *s; s = &(*s)->next) {
+		for (s = &domain->probes[index % MAX_PROBES]; *s; s = &(*s)->next) {
 			struct probe *p = *s;
 			if (p->dev == dev && p->range == range) {
 				*s = p->next;
@@ -100,7 +102,7 @@ struct kobject *kobj_lookup(struct kobj_map *domain, dev_t dev, int *index)
 
 retry:
 	mutex_lock(domain->lock);
-	for (p = domain->probes[MAJOR(dev) % 255]; p; p = p->next) {
+	for (p = domain->probes[MAJOR(dev) % MAX_PROBES]; p; p = p->next) {
 		struct kobject *(*probe)(dev_t, int *, void *);
 		struct module *owner;
 		void *data;
@@ -147,7 +149,7 @@ struct kobj_map *kobj_map_init(kobj_probe_t *base_probe, struct mutex *lock)
 	base->dev = 1;
 	base->range = ~0;
 	base->get = base_probe;
-	for (i = 0; i < 255; i++)
+	for (i = 0; i < MAX_PROBES; i++)
 		p->probes[i] = base;
 	p->lock = lock;
 	return p;
-- 
2.34.1