[PATCH v4 14/20] EDAC/mc: Add generic unique MC index allocation procedure
Serge Semin
fancer.lancer at gmail.com
Wed Sep 20 12:10:38 PDT 2023
Currently the EDAC subsystem relies on the low-level device drivers to
select an unique index for each memory controller available in the system.
Here are the already implemented approaches:
1. Fixed zero id. The vast majority of the drivers expect to have a single
memory controller in the system.
2. Calculate based on a platform-specific way (Pre-defined devices order,
PCIe-bus address, Numa node ID + PCIe-function number, etc).
3. Use platform_device->id.
4. Use custom ACPI/OF property value.
5. Use locally maintained static MC counter.
Create a generic method of the MC index allocation which could be utilized
for the case 5 (it doesn't imply any strict memory controller order) and
which would prevent the new MC EDAC drivers re-implementing the approaches
3 and 4. Moreover it will be useful for the cases when a platform is
equipped with memory-controllers of different types [1] and which are
probed by different drivers [2].
[1] Link: https://lore.kernel.org/all/9dc2a947-d2ab-4f00-8ed3-d2499cb6fdfd@BN1BFFO11FD002.protection.gbl/
[2] Link: https://lore.kernel.org/linux-edac/BY5PR12MB4258CB67B70D71F107EC1E9DDB3E9@BY5PR12MB4258.namprd12.prod.outlook.com
The suggested implementation is based on the IDA kernel API and implies
the next semantics:
1. If a particular MC index is specified it will be registered in the
IDR pool unless the specified ID has already been reserved.
2. If a special MC index is specified (EDAC_AUTO_MC_NUM) the EDAC
core will check whether there is a "mcID" alias is defined in the device
tree and use the ID from there if it's found.
3. Otherwise a next free index will be allocated and assigned to the
registered memory controller.
Signed-off-by: Serge Semin <fancer.lancer at gmail.com>
---
Note the approach implemented here has been partly ported from the SPI
core driver using IDA to track/allocate SPI bus numbers.
Link: https://elixir.bootlin.com/linux/latest/source/drivers/spi/spi.c#L2957
---
drivers/edac/edac_mc.c | 89 +++++++++++++++++++++++++++++++++++++++---
drivers/edac/edac_mc.h | 4 ++
2 files changed, 87 insertions(+), 6 deletions(-)
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 24814839d885..634c41ea7804 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -29,6 +29,9 @@
#include <linux/edac.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
+#include <linux/idr.h>
+#include <linux/of.h>
+
#include <asm/page.h>
#include "edac_mc.h"
#include "edac_module.h"
@@ -46,6 +49,7 @@ EXPORT_SYMBOL_GPL(edac_op_state);
/* lock to memory controller's control array */
static DEFINE_MUTEX(mem_ctls_mutex);
static LIST_HEAD(mc_devices);
+static DEFINE_IDR(mc_idr);
/*
* Used to lock EDAC MC to just one module, avoiding two drivers e. g.
@@ -493,7 +497,64 @@ void edac_mc_reset_delay_period(unsigned long value)
mutex_unlock(&mem_ctls_mutex);
}
+/**
+ * edac_mc_alloc_id() - Allocate unique Memory Controller identifier
+ *
+ * @mci: pointer to the mci structure to allocate ID for
+ *
+ * Use edac_mc_free_id() to coherently free the MC identifier.
+ *
+ * .. note::
+ * locking model: must be called with the mem_ctls_mutex lock held
+ *
+ * Returns:
+ * 0 on Success, or an error code on failure
+ */
+static int edac_mc_alloc_id(struct mem_ctl_info *mci)
+{
+ struct device_node *np = dev_of_node(mci->pdev);
+ int ret, min, max;
+
+ if (mci->mc_idx == EDAC_AUTO_MC_NUM) {
+ ret = of_alias_get_id(np, "mc");
+ if (ret >= 0) {
+ min = ret;
+ max = ret + 1;
+ } else {
+ min = of_alias_get_highest_id("mc");
+ if (min >= 0)
+ min++;
+ else
+ min = 0;
+
+ max = 0;
+ }
+ } else {
+ min = mci->mc_idx;
+ max = mci->mc_idx + 1;
+ }
+
+ ret = idr_alloc(&mc_idr, mci, min, max, GFP_KERNEL);
+ if (ret < 0)
+ return ret == -ENOSPC ? -EBUSY : ret;
+
+ mci->mc_idx = ret;
+
+ return 0;
+}
+/**
+ * edac_mc_free_id() - Free Memory Controller identifier
+ *
+ * @mci: pointer to the mci structure to free ID from
+ *
+ * .. note::
+ * locking model: must be called with the mem_ctls_mutex lock held
+ */
+static void edac_mc_free_id(struct mem_ctl_info *mci)
+{
+ idr_remove(&mc_idr, mci->mc_idx);
+}
/**
* edac_mc_init_labels() - Initialize DIMM labels
@@ -612,7 +673,8 @@ EXPORT_SYMBOL_GPL(edac_get_owner);
int edac_mc_add_mc_with_groups(struct mem_ctl_info *mci,
const struct attribute_group **groups)
{
- int ret = -EINVAL;
+ int ret;
+
edac_dbg(0, "\n");
#ifdef CONFIG_EDAC_DEBUG
@@ -649,20 +711,30 @@ int edac_mc_add_mc_with_groups(struct mem_ctl_info *mci,
goto fail0;
}
+ ret = edac_mc_alloc_id(mci);
+ if (ret) {
+ edac_printk(KERN_ERR, EDAC_MC, "failed to allocate MC idx %u\n",
+ mci->mc_idx);
+ goto fail0;
+ }
+
edac_mc_init_labels(mci);
- if (add_mc_to_global_list(mci))
- goto fail0;
+ if (add_mc_to_global_list(mci)) {
+ ret = -EINVAL;
+ goto fail1;
+ }
/* set load time so that error rate can be tracked */
mci->start_time = jiffies;
mci->bus = edac_get_sysfs_subsys();
- if (edac_create_sysfs_mci_device(mci, groups)) {
+ ret = edac_create_sysfs_mci_device(mci, groups);
+ if (ret) {
edac_mc_printk(mci, KERN_WARNING,
"failed to create sysfs device\n");
- goto fail1;
+ goto fail2;
}
if (mci->edac_check) {
@@ -686,9 +758,12 @@ int edac_mc_add_mc_with_groups(struct mem_ctl_info *mci,
mutex_unlock(&mem_ctls_mutex);
return 0;
-fail1:
+fail2:
del_mc_from_global_list(mci);
+fail1:
+ edac_mc_free_id(mci);
+
fail0:
mutex_unlock(&mem_ctls_mutex);
return ret;
@@ -716,6 +791,8 @@ struct mem_ctl_info *edac_mc_del_mc(struct device *dev)
if (del_mc_from_global_list(mci))
edac_mc_owner = NULL;
+ edac_mc_free_id(mci);
+
mutex_unlock(&mem_ctls_mutex);
if (mci->edac_check)
diff --git a/drivers/edac/edac_mc.h b/drivers/edac/edac_mc.h
index 881b00eadf7a..4b6676235b1b 100644
--- a/drivers/edac/edac_mc.h
+++ b/drivers/edac/edac_mc.h
@@ -23,6 +23,7 @@
#define _EDAC_MC_H_
#include <linux/kernel.h>
+#include <linux/limits.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/spinlock.h>
@@ -37,6 +38,9 @@
#include <linux/workqueue.h>
#include <linux/edac.h>
+/* Generate MC identifier automatically */
+#define EDAC_AUTO_MC_NUM UINT_MAX
+
#if PAGE_SHIFT < 20
#define PAGES_TO_MiB(pages) ((pages) >> (20 - PAGE_SHIFT))
#define MiB_TO_PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
--
2.41.0
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