linux-kernel - [PATCH v3] memory-hotplug: fix store_mem

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Date:   Thu,  1 Sep 2016 10:29:37 -0500
From:   Reza Arbab <arbab@...ux.vnet.ibm.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Yaowei Bai <baiyaowei@...s.chinamobile.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Dan Williams <dan.j.williams@...el.com>,
        Xishi Qiu <qiuxishi@...wei.com>,
        David Vrabel <david.vrabel@...rix.com>,
        Chen Yucong <slaoub@...il.com>,
        Andrew Banman <abanman@....com>,
        Seth Jennings <sjenning@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3] memory-hotplug: fix store_mem_state() return value

If store_mem_state() is called to online memory which is already online,
it will return 1, the value it got from device_online().

This is wrong because store_mem_state() is a device_attribute .store
function. Thus a non-negative return value represents input bytes read.

Set the return value to -EINVAL in this case.

Signed-off-by: Reza Arbab <arbab@...ux.vnet.ibm.com>
---
v2 -> v3:
* David Rientjes pointed out that the backwards-compatible return 
  value in this situation is -EINVAL, not success. I had mistakenly
  thought the behavior should be the same as online_store().

 drivers/base/memory.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 1cea0ba..bb69e58 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -359,8 +359,11 @@ store_mem_state(struct device *dev,
 err:
 	unlock_device_hotplug();
 
-	if (ret)
+	if (ret < 0)
 		return ret;
+	if (ret)
+		return -EINVAL;
+
 	return count;
 }
 
-- 
1.8.3.1