Date:   Wed, 26 Jul 2017 10:48:27 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     linux-edac <linux-edac@...r.kernel.org>
Cc:     Tony Luck <tony.luck@...el.com>,
        Mauro Carvalho Chehab <mchehab@...radead.org>,
        Toshimitsu Kani <toshi.kani@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 3/3] EDAC, ghes: Make it a proper module

From: Borislav Petkov <bp@...e.de>

Register with the GHES notifier chain so that there's no need to call
into the module with ghes_edac_report_mem_error().

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 drivers/acpi/apei/ghes.c |  18 +++----
 drivers/edac/Kconfig     |   4 +-
 drivers/edac/ghes_edac.c | 129 ++++++++++++++++++++++++-----------------------
 include/acpi/ghes.h      |  25 ---------
 4 files changed, 74 insertions(+), 102 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 3f05f5ff3461..37cd698cacd2 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -475,11 +475,11 @@ static void ghes_handle_memory_failure(struct acpi_hest_generic_data *gdata, int
 static void ghes_do_proc(struct ghes *ghes,
 			 const struct acpi_hest_generic_status *estatus)
 {
-	int sev, sec_sev;
 	struct acpi_hest_generic_data *gdata;
 	guid_t *sec_type;
 	guid_t *fru_id = &NULL_UUID_LE;
 	char *fru_text = "";
+	int sev, sec_sev;
 
 	sev = ghes_severity(estatus->error_severity);
 	apei_estatus_for_each_section(estatus, gdata) {
@@ -494,7 +494,8 @@ static void ghes_do_proc(struct ghes *ghes,
 		if (guid_equal(sec_type, &CPER_SEC_PLATFORM_MEM)) {
 			struct cper_sec_mem_err *mem_err = acpi_hest_get_payload(gdata);
 
-			ghes_edac_report_mem_error(ghes, sev, mem_err);
+
+			atomic_notifier_call_chain(&ghes_edac_chain, sev, &mem_err);
 
 			arch_apei_report_mem_error(sev, mem_err);
 			ghes_handle_memory_failure(gdata, sev);
@@ -1153,10 +1154,6 @@ static int ghes_probe(struct platform_device *ghes_dev)
 		goto err;
 	}
 
-	rc = ghes_edac_register(ghes, &ghes_dev->dev);
-	if (rc < 0)
-		goto err;
-
 	switch (generic->notify.type) {
 	case ACPI_HEST_NOTIFY_POLLED:
 		setup_deferrable_timer(&ghes->timer, ghes_poll_func,
@@ -1169,13 +1166,13 @@ static int ghes_probe(struct platform_device *ghes_dev)
 		if (rc) {
 			pr_err(GHES_PFX "Failed to map GSI to IRQ for generic hardware error source: %d\n",
 			       generic->header.source_id);
-			goto err_edac_unreg;
+			goto err;
 		}
 		rc = request_irq(ghes->irq, ghes_irq_func, 0, "GHES IRQ", ghes);
 		if (rc) {
 			pr_err(GHES_PFX "Failed to register IRQ for generic hardware error source: %d\n",
 			       generic->header.source_id);
-			goto err_edac_unreg;
+			goto err;
 		}
 		break;
 
@@ -1204,8 +1201,7 @@ static int ghes_probe(struct platform_device *ghes_dev)
 	ghes_proc(ghes);
 
 	return 0;
-err_edac_unreg:
-	ghes_edac_unregister(ghes);
+
 err:
 	if (ghes) {
 		ghes_fini(ghes);
@@ -1255,8 +1251,6 @@ static int ghes_remove(struct platform_device *ghes_dev)
 
 	ghes_fini(ghes);
 
-	ghes_edac_unregister(ghes);
-
 	kfree(ghes);
 
 	platform_set_drvdata(ghes_dev, NULL);
diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
index 96afb2aeed18..fdd8278ca89a 100644
--- a/drivers/edac/Kconfig
+++ b/drivers/edac/Kconfig
@@ -53,8 +53,8 @@ config EDAC_DECODE_MCE
 	  has been initialized.
 
 config EDAC_GHES
-	bool "Output ACPI APEI/GHES BIOS detected errors via EDAC"
-	depends on ACPI_APEI_GHES && (EDAC=y)
+	tristate "Output ACPI APEI/GHES BIOS detected errors via EDAC"
+	depends on ACPI_APEI_GHES
 	help
 	  Not all machines support hardware-driven error report. Some of those
 	  provide a BIOS-driven error report mechanism via ACPI, using the
diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
index 6f80eb65c26c..ecd34b8bd27e 100644
--- a/drivers/edac/ghes_edac.c
+++ b/drivers/edac/ghes_edac.c
@@ -5,6 +5,9 @@
  * License version 2.
  *
  * Copyright (c) 2013 by Mauro Carvalho Chehab
+ *	     (c) 2017 Borislav Petkov
+ *
+ * Borislav Petkov: turn it into a proper module.
  *
  * Red Hat Inc. http://www.redhat.com
  */
@@ -28,10 +31,10 @@ struct ghes_edac_pvt {
 	char msg[80];
 };
 
-static LIST_HEAD(ghes_reglist);
-static DEFINE_MUTEX(ghes_edac_lock);
-static int ghes_edac_mc_num;
+static struct ghes_edac_pvt *ghes_pvt;
 
+/* Hand it into EDAC's core so that we have a device to operate on. */
+static struct device dummy_dev;
 
 /* Memory Device - Type 17 of SMBIOS spec */
 struct memdev_dmi_entry {
@@ -163,24 +166,21 @@ static void ghes_edac_dmidecode(const struct dmi_header *dh, void *arg)
 	}
 }
 
-void ghes_edac_report_mem_error(struct ghes *ghes, int sev,
-				struct cper_sec_mem_err *mem_err)
+static int report_mem_error(struct notifier_block *nb, unsigned long sev, void *data)
 {
+	struct cper_sec_mem_err *mem_err = data;
 	enum hw_event_mc_err_type type;
 	struct edac_raw_error_desc *e;
 	struct mem_ctl_info *mci;
-	struct ghes_edac_pvt *pvt = NULL;
-	char *p;
+	struct ghes_edac_pvt *pvt = ghes_pvt;
 	u8 grain_bits;
+	char *p;
 
-	list_for_each_entry(pvt, &ghes_reglist, list) {
-		if (ghes == pvt->ghes)
-			break;
-	}
 	if (!pvt) {
-		pr_err("Internal error: Can't find EDAC structure\n");
-		return;
+		edac_pr_err("Internal error: Can't find EDAC structure\n");
+		return NOTIFY_DONE;
 	}
+
 	mci = pvt->mci;
 	e = &mci->error_desc;
 
@@ -400,23 +400,40 @@ void ghes_edac_report_mem_error(struct ghes *ghes, int sev,
 
 	/* Report the error via EDAC API */
 	edac_raw_mc_handle_error(type, mci, e);
+
+	return NOTIFY_DONE;
 }
-EXPORT_SYMBOL_GPL(ghes_edac_report_mem_error);
 
-int ghes_edac_register(struct ghes *ghes, struct device *dev)
+static struct notifier_block ghes_nb = {
+	.notifier_call  = report_mem_error,
+};
+
+static const char * const fake_msg =
+"This EDAC driver relies on BIOS to enumerate memory and get error reports.\n"
+"Unfortunately, not all BIOSes reflect the memory layout correctly.\n"
+"So, the end result of using this driver varies from vendor to vendor.\n"
+"If you find incorrect reports, please contact your hardware vendor\n"
+"to correct its BIOS.";
+
+static const char * const super_crap_msg =
+"This system has a very crappy BIOS: It doesn't even list the DIMMS.\n"
+"Its SMBIOS info is wrong. It is doubtful that the error report would\n"
+"work on such system. Use this driver with caution.";
+
+static int __init ghes_edac_register(void)
 {
+	struct ghes_edac_pvt *pvt = ghes_pvt;
 	bool fake = false;
 	int rc, num_dimm = 0;
 	struct mem_ctl_info *mci;
 	struct edac_mc_layer layers[1];
-	struct ghes_edac_pvt *pvt;
 	struct ghes_edac_dimm_fill dimm_fill;
 
 	/* Get the number of DIMMs */
 	dmi_walk(ghes_edac_count_dimms, &num_dimm);
 
 	/* Check if we've got a bogus BIOS */
-	if (num_dimm == 0) {
+	if (!num_dimm) {
 		fake = true;
 		num_dimm = 1;
 	}
@@ -429,21 +446,17 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
 	 * We need to serialize edac_mc_alloc() and edac_mc_add_mc(),
 	 * to avoid duplicated memory controller numbers
 	 */
-	mutex_lock(&ghes_edac_lock);
-	mci = edac_mc_alloc(ghes_edac_mc_num, ARRAY_SIZE(layers), layers,
-			    sizeof(*pvt));
+	mci = edac_mc_alloc(1, ARRAY_SIZE(layers), layers, sizeof(*pvt));
 	if (!mci) {
-		pr_info("Can't allocate memory for EDAC data\n");
-		mutex_unlock(&ghes_edac_lock);
+		edac_pr_err("Can't allocate memory for EDAC data\n");
 		return -ENOMEM;
 	}
 
 	pvt = mci->pvt_info;
 	memset(pvt, 0, sizeof(*pvt));
-	list_add_tail(&pvt->list, &ghes_reglist);
-	pvt->ghes = ghes;
 	pvt->mci  = mci;
-	mci->pdev = dev;
+
+	mci->pdev = &dummy_dev;
 
 	mci->mtype_cap = MEM_FLAG_EMPTY;
 	mci->edac_ctl_cap = EDAC_FLAG_NONE;
@@ -452,21 +465,12 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
 	mci->ctl_name = "ghes_edac";
 	mci->dev_name = "ghes";
 
-	if (!ghes_edac_mc_num) {
-		if (!fake) {
-			pr_info("This EDAC driver relies on BIOS to enumerate memory and get error reports.\n");
-			pr_info("Unfortunately, not all BIOSes reflect the memory layout correctly.\n");
-			pr_info("So, the end result of using this driver varies from vendor to vendor.\n");
-			pr_info("If you find incorrect reports, please contact your hardware vendor\n");
-			pr_info("to correct its BIOS.\n");
-			pr_info("This system has %d DIMM sockets.\n",
-				num_dimm);
-		} else {
-			pr_info("This system has a very crappy BIOS: It doesn't even list the DIMMS.\n");
-			pr_info("Its SMBIOS info is wrong. It is doubtful that the error report would\n");
-			pr_info("work on such system. Use this driver with caution\n");
-		}
-	}
+	if (!fake)
+		edac_pr_info("%s\n", fake_msg);
+	else
+		edac_pr_info("%s\n", super_crap_msg);
+
+	edac_pr_info("This system has %d DIMM sockets.\n", num_dimm);
 
 	if (!fake) {
 		/*
@@ -475,13 +479,11 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
 		 * Keep it in blank for the other memory controllers, as
 		 * there's no reliable way to properly credit each DIMM to
 		 * the memory controller, as different BIOSes fill the
-		 * DMI bank location fields on different ways
+		 * DMI bank location fields in different ways.
 		 */
-		if (!ghes_edac_mc_num) {
-			dimm_fill.count = 0;
-			dimm_fill.mci = mci;
-			dmi_walk(ghes_edac_dmidecode, &dimm_fill);
-		}
+		dimm_fill.count = 0;
+		dimm_fill.mci = mci;
+		dmi_walk(ghes_edac_dmidecode, &dimm_fill);
 	} else {
 		struct dimm_info *dimm = EDAC_DIMM_PTR(mci->layers, mci->dimms,
 						       mci->n_layers, 0, 0, 0);
@@ -495,30 +497,31 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
 
 	rc = edac_mc_add_mc(mci);
 	if (rc < 0) {
-		pr_info("Can't register at EDAC core\n");
+		edac_pr_err("Can't register with EDAC core\n");
 		edac_mc_free(mci);
-		mutex_unlock(&ghes_edac_lock);
 		return -ENODEV;
 	}
 
-	ghes_edac_mc_num++;
-	mutex_unlock(&ghes_edac_lock);
+	ghes_register_edac_chain(&ghes_nb);
+
 	return 0;
 }
-EXPORT_SYMBOL_GPL(ghes_edac_register);
+module_init(ghes_edac_register);
 
-void ghes_edac_unregister(struct ghes *ghes)
+static void __exit ghes_edac_unregister(void)
 {
 	struct mem_ctl_info *mci;
-	struct ghes_edac_pvt *pvt, *tmp;
-
-	list_for_each_entry_safe(pvt, tmp, &ghes_reglist, list) {
-		if (ghes == pvt->ghes) {
-			mci = pvt->mci;
-			edac_mc_del_mc(mci->pdev);
-			edac_mc_free(mci);
-			list_del(&pvt->list);
-		}
-	}
+
+	ghes_unregister_edac_chain(&ghes_nb);
+
+	mci = find_mci_by_dev(&dummy_dev);
+	WARN_ON(!mci);
+
+	edac_mc_del_mc(mci->pdev);
+	edac_mc_free(mci);
+
 }
-EXPORT_SYMBOL_GPL(ghes_edac_unregister);
+module_exit(ghes_edac_unregister);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("GHES error decoding module");
diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
index 506b6a197738..c02b8eb91bd6 100644
--- a/include/acpi/ghes.h
+++ b/include/acpi/ghes.h
@@ -51,31 +51,6 @@ enum {
 	GHES_SEV_PANIC = 0x3,
 };
 
-/* From drivers/edac/ghes_edac.c */
-
-#ifdef CONFIG_EDAC_GHES
-void ghes_edac_report_mem_error(struct ghes *ghes, int sev,
-				struct cper_sec_mem_err *mem_err);
-
-int ghes_edac_register(struct ghes *ghes, struct device *dev);
-
-void ghes_edac_unregister(struct ghes *ghes);
-
-#else
-static inline void ghes_edac_report_mem_error(struct ghes *ghes, int sev,
-				       struct cper_sec_mem_err *mem_err)
-{
-}
-
-static inline int ghes_edac_register(struct ghes *ghes, struct device *dev)
-{
-	return 0;
-}
-
-static inline void ghes_edac_unregister(struct ghes *ghes)
-{
-}
-#endif
 void ghes_register_edac_chain(struct notifier_block *nb);
 void ghes_unregister_edac_chain(struct notifier_block *nb);
 
-- 
2.14.0.rc0

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