[PATCH] EDAC/device: Add sysfs notification for UE,CE count change

[Deepti Jaggi]

A daemon running in user space collects information on correctable
and uncorrectable errors from EDAC driver by reading corresponding
sysfs entries and takes appropriate action.
This patch adds support for user space daemon to wait on poll() until
the sysfs entries for UE count and CE count change and then read updated
counts instead of continuously monitoring the sysfs entries for
any changes.

Signed-off-by: Deepti Jaggi <quic_djaggi@xxxxxxxxxxx>
---
 drivers/edac/edac_device.c       | 16 ++++++++++++++++
 drivers/edac/edac_device.h       |  8 ++++++++
 drivers/edac/edac_device_sysfs.c | 20 ++++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/drivers/edac/edac_device.c b/drivers/edac/edac_device.c
index 8c4d947fb848..7b7aec4da6b9 100644
--- a/drivers/edac/edac_device.c
+++ b/drivers/edac/edac_device.c
@@ -587,12 +587,20 @@ void edac_device_handle_ce_count(struct edac_device_ctl_info *edac_dev,
 	if (instance->nr_blocks > 0) {
 		block = instance->blocks + block_nr;
 		block->counters.ce_count += count;
+
+		/* Notify block sysfs attribute change */
+		if (block->kn_ce)
+			sysfs_notify_dirent(block->kn_ce);
 	}
 
 	/* Propagate the count up the 'totals' tree */
 	instance->counters.ce_count += count;
 	edac_dev->counters.ce_count += count;
 
+	/* Notify instance sysfs attribute change */
+	if (instance->kn_ce)
+		sysfs_notify_dirent(instance->kn_ce);
+
 	if (edac_device_get_log_ce(edac_dev))
 		edac_device_printk(edac_dev, KERN_WARNING,
 				   "CE: %s instance: %s block: %s count: %d '%s'\n",
@@ -633,12 +641,20 @@ void edac_device_handle_ue_count(struct edac_device_ctl_info *edac_dev,
 	if (instance->nr_blocks > 0) {
 		block = instance->blocks + block_nr;
 		block->counters.ue_count += count;
+
+		/* Notify block sysfs attribute change */
+		if (block->kn_ue)
+			sysfs_notify_dirent(block->kn_ue);
 	}
 
 	/* Propagate the count up the 'totals' tree */
 	instance->counters.ue_count += count;
 	edac_dev->counters.ue_count += count;
 
+	/* Notify instance sysfs attribute change */
+	if (instance->kn_ue)
+		sysfs_notify_dirent(instance->kn_ue);
+
 	if (edac_device_get_log_ue(edac_dev))
 		edac_device_printk(edac_dev, KERN_EMERG,
 				   "UE: %s instance: %s block: %s count: %d '%s'\n",
diff --git a/drivers/edac/edac_device.h b/drivers/edac/edac_device.h
index fc2d2c218064..459514ea549e 100644
--- a/drivers/edac/edac_device.h
+++ b/drivers/edac/edac_device.h
@@ -127,6 +127,10 @@ struct edac_device_block {
 
 	/* edac sysfs device control */
 	struct kobject kobj;
+
+	/* kern fs node for block ue_count and ce count attributes*/
+	struct kernfs_node *kn_ue;
+	struct kernfs_node *kn_ce;
 };
 
 /* device instance control structure */
@@ -141,6 +145,10 @@ struct edac_device_instance {
 
 	/* edac sysfs device control */
 	struct kobject kobj;
+
+	/* kern fs node for block ue_count and ce count attributes*/
+	struct kernfs_node *kn_ue;
+	struct kernfs_node *kn_ce;
 };
 
 
diff --git a/drivers/edac/edac_device_sysfs.c b/drivers/edac/edac_device_sysfs.c
index 5e7593753799..d1e04a9296c7 100644
--- a/drivers/edac/edac_device_sysfs.c
+++ b/drivers/edac/edac_device_sysfs.c
@@ -562,6 +562,13 @@ static int edac_device_create_block(struct edac_device_ctl_info *edac_dev,
 	}
 	kobject_uevent(&block->kobj, KOBJ_ADD);
 
+	/*
+	 * Save kernfs pointer for ue count and ce count
+	 * to notify from any context when attributes change
+	 */
+	block->kn_ue = sysfs_get_dirent(block->kobj.sd, "ue_count");
+	block->kn_ce = sysfs_get_dirent(block->kobj.sd, "ce_count");
+
 	return 0;
 
 	/* Error unwind stack */
@@ -594,6 +601,9 @@ static void edac_device_delete_block(struct edac_device_ctl_info *edac_dev,
 		}
 	}
 
+	block->kn_ue = NULL;
+	block->kn_ce = NULL;
+
 	/* unregister this block's kobject, SEE:
 	 *	edac_device_ctrl_block_release() callback operation
 	 */
@@ -660,6 +670,13 @@ static int edac_device_create_instance(struct edac_device_ctl_info *edac_dev,
 	edac_dbg(4, "Registered instance %d '%s' kobject\n",
 		 idx, instance->name);
 
+	/*
+	 * Save kernfs pointer for ue count and ce count
+	 * to notify from any context when attributes change
+	 */
+	instance->kn_ue = sysfs_get_dirent(instance->kobj.sd, "ue_count");
+	instance->kn_ce = sysfs_get_dirent(instance->kobj.sd, "ce_count");
+
 	return 0;
 
 	/* error unwind stack */
@@ -682,6 +699,9 @@ static void edac_device_delete_instance(struct edac_device_ctl_info *edac_dev,
 
 	instance = &edac_dev->instances[idx];
 
+	instance->kn_ue = NULL;
+	instance->kn_ce = NULL;
+
 	/* unregister all blocks in this instance */
 	for (i = 0; i < instance->nr_blocks; i++)
 		edac_device_delete_block(edac_dev, &instance->blocks[i]);
-- 
2.31.1