[PATCH v2 1/2] EDAC: Fix sysfs dimm_label show operation

[Toshi Kani]

After 'commit 7d375bffa524 ("sb_edac: Fix support for systems with
two home agents per socket")', sysfs "dimm_label" and "chX_dimm_label"
show their label string without a newline "\n" at the end.

 [root@orange ~]# cat /sys/bus/mc0/devices/dimm0/dimm_label
 CPU_SrcID#0_Ha#0_Chan#0_DIMM#0[root@orange ~]#

 [root@orange ~]# cat /sys/devices/system/edac/mc/mc0/csrow0/ch0_dimm_label
 CPU_SrcID#0_Ha#0_Chan#0_DIMM#0[root@orange ~]#

The label strings now have 31 characters, which are the same as
EDAC_MC_LABEL_LEN.  Since the snprintf()s in channel_dimm_label_show()
and dimmdev_label_show() limit the whole length by EDAC_MC_LABEL_LEN,
the newline in the format "%s\n" is ignored.

 [root@orange ~]# od -bc /sys/bus/mc0/devices/dimm0/dimm_label
 0000000 103 120 125 137 123 162 143 111 104 043 060 137 110 141 043 060
           C   P   U   _   S   r   c   I   D   #   0   _   H   a   #   0
 0000020 137 103 150 141 156 043 060 137 104 111 115 115 043 060 000
           _   C   h   a   n   #   0   _   D   I   M   M   #   0  \0
 0000037

Fix it by using 'sizeof(dimm->label) + 1' as the whole length in
the snprintf()s in channel_dimm_label_show() and dimmdev_label_show().

Reported-by: Robert Elliott <elliott@xxxxxxx>
Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
Acked-by: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Doug Thompson <dougthompson@xxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Robert Elliott <elliott@xxxxxxx>
---
 drivers/edac/edac_mc_sysfs.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index 33df7d9..8983755 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -229,7 +229,7 @@ static ssize_t channel_dimm_label_show(struct device *dev,
 	if (!rank->dimm->label[0])
 		return 0;
 
-	return snprintf(data, EDAC_MC_LABEL_LEN, "%s\n",
+	return snprintf(data, sizeof(rank->dimm->label) + 1, "%s\n",
 			rank->dimm->label);
 }
 
@@ -485,7 +485,7 @@ static ssize_t dimmdev_label_show(struct device *dev,
 	if (!dimm->label[0])
 		return 0;
 
-	return snprintf(data, EDAC_MC_LABEL_LEN, "%s\n", dimm->label);
+	return snprintf(data, sizeof(dimm->label) + 1, "%s\n", dimm->label);
 }
 
 static ssize_t dimmdev_label_store(struct device *dev,
--
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