Commit 1f6a6cc8 authored by Tang Chen's avatar Tang Chen Committed by Linus Torvalds
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mem-hotplug: avoid illegal state prefixed with legal state when changing state of memory_block

We use the following command to online a memory_block:

    echo online|online_kernel|online_movable > /sys/devices/system/memory/memoryXXX/state

But, if we do the following:

    echo online_fhsjkghfkd > /sys/devices/system/memory/memoryXXX/state

the block will also be onlined.

This is because the following code in store_mem_state() does not compare
the whole string, but only the prefix of the string.

   328         if (!strncmp(buf, "online_kernel", min_t(int, count, 13)))

Here, only compare the first 13 letters of the string. If we give "online_kernelXXXXXX",
it will be recognized as online_kernel, which is incorrect.

   329                 online_type = ONLINE_KERNEL;
   330         else if (!strncmp(buf, "online_movable", min_t(int, count, 14)))

We have the same problem here,

   331                 online_type = ONLINE_MOVABLE;
   332         else if (!strncmp(buf, "online", min_t(int, count, 6)))


(Here is more problematic.  If we give online_movalbe, which is a typo
of online_movable, it will be recognized as online without noticing the

   333                 online_type = ONLINE_KEEP;
   334         else if (!strncmp(buf, "offline", min_t(int, count, 7)))

and here.

   335                 online_type = -1;
   336         else {
   337                 ret = -EINVAL;
   338                 goto err;
   339         }

This patch fixes this problem by using sysfs_streq() to compare the
whole string.
Signed-off-by: default avatarTang Chen <>
Reported-by: default avatarHu Tao <>
Cc: Greg Kroah-Hartman <>
Cc: Lai Jiangshan <>
Cc: Yasuaki Ishimatsu <>
Cc: Gu Zheng <>
Acked-by: default avatarToshi Kani <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent c0d73261
......@@ -315,13 +315,13 @@ store_mem_state(struct device *dev,
if (ret)
return ret;
if (!strncmp(buf, "online_kernel", min_t(int, count, 13)))
if (sysfs_streq(buf, "online_kernel"))
online_type = ONLINE_KERNEL;
else if (!strncmp(buf, "online_movable", min_t(int, count, 14)))
else if (sysfs_streq(buf, "online_movable"))
online_type = ONLINE_MOVABLE;
else if (!strncmp(buf, "online", min_t(int, count, 6)))
else if (sysfs_streq(buf, "online"))
online_type = ONLINE_KEEP;
else if (!strncmp(buf, "offline", min_t(int, count, 7)))
else if (sysfs_streq(buf, "offline"))
online_type = -1;
else {
ret = -EINVAL;
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