[PATCH] memory-hotplug: fix store_mem_state() return value

[Reza Arbab <arbab@linux.vnet.ibm.com>]

Attempting to online memory which is already online will cause this:

1. store_mem_state() called with buf="online"
2. device_online() returns 1 because device is already online
3. store_mem_state() returns 1
4. calling code interprets this as 1-byte buffer read
5. store_mem_state() called again with buf="nline"
6. store_mem_state() returns -EINVAL

Example:

$ cat /sys/devices/system/memory/memory0/state
online
$ echo online > /sys/devices/system/memory/memory0/state
-bash: echo: write error: Invalid argument

Fix the return value of store_mem_state() so this doesn't happen.

Signed-off-by: Reza Arbab <arbab@linux.vnet.ibm.com>
---
 drivers/base/memory.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 961e2cf..031950f 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -359,9 +359,7 @@ store_mem_state(struct device *dev,
 err:
 	unlock_device_hotplug();
 
-	if (ret)
-		return ret;
-	return count;
+	return ret < 0 ? ret : count;
 }
 
 /*
-- 
1.8.3.1