linux-kernel - [PATCH v2] drivers/base/memory: Use array to show memory block state

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Message-Id: <20230120233814.368803-1-gshan@redhat.com>
Date:   Sat, 21 Jan 2023 07:38:14 +0800
From:   Gavin Shan <gshan@...hat.com>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, david@...hat.com, osalvador@...e.de,
        gregkh@...uxfoundation.org, rafael@...nel.org, shan.gavin@...il.com
Subject: [PATCH v2] drivers/base/memory: Use array to show memory block state

Use an array to show memory block state from '/sys/devices/system/
memory/memoryX/state', to simplify the code. Besides, WARN_ON()
is removed since the warning can be caught by the return value,
which is "ERROR-UNKNOWN-%ld\n". A system reboot caused by WARN_ON()
is definitely unexpected as Greg mentioned.

No functional change intended.

Signed-off-by: Gavin Shan <gshan@...hat.com>
---
v2: Drop WARN_ON()					(Greg)
---
 drivers/base/memory.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index b456ac213610..0fdacdc79806 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -141,28 +141,15 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
 	struct memory_block *mem = to_memory_block(dev);
-	const char *output;
+	static const char *const mem_state_str[] = {
+		NULL, "online", "going-offline", NULL, "offline",
+	};
 
-	/*
-	 * We can probably put these states in a nice little array
-	 * so that they're not open-coded
-	 */
-	switch (mem->state) {
-	case MEM_ONLINE:
-		output = "online";
-		break;
-	case MEM_OFFLINE:
-		output = "offline";
-		break;
-	case MEM_GOING_OFFLINE:
-		output = "going-offline";
-		break;
-	default:
-		WARN_ON(1);
+	if (mem->state >= ARRAY_SIZE(mem_state_str) ||
+	    !mem_state_str[mem->state])
 		return sysfs_emit(buf, "ERROR-UNKNOWN-%ld\n", mem->state);
-	}
 
-	return sysfs_emit(buf, "%s\n", output);
+	return sysfs_emit(buf, "%s\n", mem_state_str[mem->state]);
 }
 
 int memory_notify(unsigned long val, void *v)
-- 
2.23.0