[PATCH v3 25/31] edac: Add a sysfs node to test the EDAC error report facility

[Mauro Carvalho Chehab <mchehab@redhat.com>]

Not all hardware supports error injection. Also, this feature
could be disabled by the BIOS. As we need to test the EDAC
error report facilities and the edac utils logic, add a way
to generate fake errors, when EDAC debug is enabled.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
---
 drivers/edac/edac_mc_sysfs.c |   62 ++++++++++++++++++++++++++++++++++++++++-
 include/linux/edac.h         |    4 +++
 2 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index 4e8f0ec..f8132ff 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -744,6 +744,42 @@ static ssize_t mci_size_mb_show(struct mem_ctl_info *mci, char *data,
 	return sprintf(data, "%u\n", PAGES_TO_MiB(total_pages));
 }
 
+#ifdef CONFIG_EDAC_DEBUG
+static ssize_t edac_fake_inject_show(struct mem_ctl_info *mci,
+				     char *data, void *priv)
+{
+	return sprintf(data,
+		       "EDAC fake test engine. Writing to this node a value in the form of :\n"
+		       "\t0:1:0\n"
+		       "will call the EDAC core routine to produce a memory error for the given memory location (0, 1, 0).\n"
+		       "The driver's error parsing logic won't be tested. This tool is useful only\n"
+		       "if you're testing the EDAC core tracing facility, or if you're needing to test\n"
+		       "some userspace application.\n");
+}
+
+static ssize_t edac_fake_inject_store(struct mem_ctl_info *mci,
+				      const char *data, size_t count,
+				      void *priv)
+{
+	static enum hw_event_mc_err_type type = HW_EVENT_ERR_CORRECTED;
+	int err, layer0 = -1, layer1 = -1, layer2= -1;
+	err = sscanf(data, "%i:%i:%i", &layer0, &layer1, &layer2);
+	if (err < 0)
+		return err;
+
+	printk(KERN_DEBUG
+	       "Generating a fake error to %d.%d.%d to test core handling. NOTE: this won't test the driver-specific decoding logic.\n",
+	       layer0, layer1, layer2);
+	edac_mc_handle_error(type, mci, 0, 0, 0,
+			     layer0, layer1, layer2,
+			     "FAKE ERROR", "for EDAC testing only", NULL);
+	if (++type == HW_EVENT_ERR_FATAL)
+		type = HW_EVENT_ERR_CORRECTED;
+
+	return count;
+}
+#endif
+
 #define to_mci(k) container_of(k, struct mem_ctl_info, edac_mci_kobj)
 #define to_mcidev_attr(a) container_of(a,struct mcidev_sysfs_attribute,attr)
 
@@ -875,7 +911,7 @@ static int edac_create_errcount_layer(struct mem_ctl_info *mci,
 		debugf4("%s() creating %s\n", __func__, (*erc)->attr.name);
 		if (!(*erc)->attr.name)
 			return -ENOMEM;
-		(*erc)->attr.mode = S_IRUGO;
+		(*erc)->attr.mode = S_IRUGO | S_IWUSR;
 		(*erc)->show = errcount_ce_show;
 		(*erc)->priv = *ercd;
 		(*ercd)->n_layers = layer + 1;
@@ -1320,7 +1356,24 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci)
 			goto fail2;
 		}
 	}
-	edac_create_errcount_objects(mci);
+	err = edac_create_errcount_objects(mci);
+	if (err) {
+		debugf1("%s() failure: create error count objects\n",
+			__func__);
+		goto fail2;
+	}
+#ifdef CONFIG_EDAC_DEBUG
+	mci->errinject_attr.attr.name = "fake_inject";
+	mci->errinject_attr.attr.mode = S_IRUGO | S_IWUSR;
+	mci->errinject_attr.show = edac_fake_inject_show;
+	mci->errinject_attr.store = edac_fake_inject_store;
+	err = sysfs_create_file(&mci->edac_mci_kobj, &mci->errinject_attr.attr);
+	if (err < 0) {
+		printk(KERN_ERR
+		       "sysfs_create_file for fake inject failed: %d\n", err);
+		mci->errinject_attr.attr.name = NULL;
+	}
+#endif
 
 	return 0;
 
@@ -1366,6 +1419,11 @@ void edac_remove_sysfs_mci_device(struct mem_ctl_info *mci)
 
 	debugf0("%s()\n", __func__);
 
+#ifdef CONFIG_EDAC_DEBUG
+	if (mci->errinject_attr.attr.name)
+		sysfs_remove_file(&mci->edac_mci_kobj,
+				  &mci->errinject_attr.attr);
+#endif
 	edac_remove_errcount(mci);
 
 	/* remove all dimms kobjects */
diff --git a/include/linux/edac.h b/include/linux/edac.h
index 790e1c2..6f03768 100644
--- a/include/linux/edac.h
+++ b/include/linux/edac.h
@@ -597,6 +597,10 @@ struct mem_ctl_info {
 	struct mcidev_sysfs_attribute *errcount_attr;
 	struct errcount_attribute_data *errcount_attr_data;
 
+#ifdef CONFIG_EDAC_DEBUG
+	struct mcidev_sysfs_attribute errinject_attr;
+#endif
+
 	struct completion complete;
 
 	/* edac sysfs device control */
-- 
1.7.8