linux-kernel - [RFC PATCH v3 10/10] EDAC/amd64: Check for memory before fully initializing an instance

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Date:   Thu, 22 Aug 2019 00:00:03 +0000
From:   "Ghannam, Yazen" <Yazen.Ghannam@....com>
To:     "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>
CC:     "Ghannam, Yazen" <Yazen.Ghannam@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bp@...en8.de" <bp@...en8.de>
Subject: [RFC PATCH v3 10/10] EDAC/amd64: Check for memory before fully
 initializing an instance

From: Yazen Ghannam <yazen.ghannam@....com>

Return early before checking for ECC if the node does not have any
populated memory.

Free any cached hardware data before returning. Also, return 0 in this
case since this is not a failure. Other nodes may have memory and the
module should attempt to load an instance for them.

Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
---
 drivers/edac/amd64_edac.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index c1cb0234f085..7230ed4ff665 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -3505,6 +3505,23 @@ static int init_one_instance(struct amd64_pvt *pvt,
 	return ret;
 }
 
+static bool instance_has_memory(struct amd64_pvt *pvt)
+{
+	bool cs_enabled = false;
+	int num_channels = 2;
+	int cs = 0, dct = 0;
+
+	if (pvt->umc)
+		num_channels = num_umcs;
+
+	for (dct = 0; dct < num_channels; dct++) {
+		for_each_chip_select(cs, dct, pvt)
+			cs_enabled |= csrow_enabled(cs, dct, pvt);
+	}
+
+	return cs_enabled;
+}
+
 static int probe_one_instance(unsigned int nid)
 {
 	struct pci_dev *F3 = node_to_amd_nb(nid)->misc;
@@ -3535,6 +3552,10 @@ static int probe_one_instance(unsigned int nid)
 	if (ret < 0)
 		goto err_enable;
 
+	ret = 0;
+	if (!instance_has_memory(pvt))
+		goto err_enable;
+
 	if (!ecc_enabled(pvt)) {
 		ret = 0;
 
-- 
2.17.1