linux/debian/patches/bugfix/x86/amd64_edac-Fix-single-chann...

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From: Borislav Petkov <bp@suse.de>
Date: Tue, 23 Jul 2013 20:01:23 +0200
Subject: amd64_edac: Fix single-channel setups
Origin: https://git.kernel.org/linus/f0a56c480196a98479760862468cc95879df3de0
Bug-Debian: http://bugs.debian.org/717473
It can happen that configurations are running in a single-channel mode
even with a dual-channel memory controller, by, say, putting the DIMMs
only on the one channel and leaving the other empty. This causes a
problem in init_csrows which implicitly assumes that when the second
channel is enabled, i.e. channel 1, the struct dimm hierarchy will be
present. Which is not.
So always allocate two channels unconditionally.
This provides for the nice side effect that the data structures are
initialized so some day, when memory hotplug is supported, it should
just work out of the box when all of a sudden a second channel appears.
Reported-and-tested-by: Roger Leigh <rleigh@debian.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
drivers/edac/amd64_edac.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index 8b6a034..8b3d901 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -2470,8 +2470,15 @@ static int amd64_init_one_instance(struct pci_dev *F2)
layers[0].size = pvt->csels[0].b_cnt;
layers[0].is_virt_csrow = true;
layers[1].type = EDAC_MC_LAYER_CHANNEL;
- layers[1].size = pvt->channel_count;
+
+ /*
+ * Always allocate two channels since we can have setups with DIMMs on
+ * only one channel. Also, this simplifies handling later for the price
+ * of a couple of KBs tops.
+ */
+ layers[1].size = 2;
layers[1].is_virt_csrow = false;
+
mci = edac_mc_alloc(nid, ARRAY_SIZE(layers), layers, 0);
if (!mci)
goto err_siblings;