[PATCH v3 14/16] powernv/opalcore: provide an option to invalidate /sys/firmware/opal/core file

[Hari Bathini]

Writing '1' to /sys/kernel/fadump_release_opalcore would release the
memory held by kernel in exporting /sys/firmware/opal/core file.

Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
---
 arch/powerpc/platforms/powernv/opal-core.c |   40 +++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/opal-core.c b/arch/powerpc/platforms/powernv/opal-core.c
index 56fb1cd..f3e336c 100644
--- a/arch/powerpc/platforms/powernv/opal-core.c
+++ b/arch/powerpc/platforms/powernv/opal-core.c
@@ -19,6 +19,8 @@
 #include <linux/proc_fs.h>
 #include <linux/elf.h>
 #include <linux/elfcore.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
 #include <linux/slab.h>
 #include <linux/crash_core.h>
 #include <linux/of.h>
@@ -172,7 +174,7 @@ static ssize_t read_opalcore(struct file *file, struct kobject *kobj,
 	if (pos >= oc_conf->opalcore_size)
 		return 0;
 
-	/* Adjust count if it goes beyond opacore size */
+	/* Adjust count if it goes beyond opalcore size */
 	avail = oc_conf->opalcore_size - pos;
 	if (count > avail)
 		count = avail;
@@ -559,6 +561,36 @@ static void opalcore_cleanup(void)
 }
 __exitcall(opalcore_cleanup);
 
+static ssize_t fadump_release_opalcore_store(struct kobject *kobj,
+					     struct kobj_attribute *attr,
+					     const char *buf, size_t count)
+{
+	int input = -1;
+
+	if (kstrtoint(buf, 0, &input))
+		return -EINVAL;
+
+	if (input == 1) {
+		if (oc_conf == NULL) {
+			pr_err("'/proc/opalcore' file does not exist!\n");
+			return -EPERM;
+		}
+
+		/*
+		 * Take away '/proc/opalcore' and release all memory
+		 * used for exporting this file.
+		 */
+		opalcore_cleanup();
+	} else
+		return -EINVAL;
+
+	return count;
+}
+
+static struct kobj_attribute opalcore_rel_attr = __ATTR(fadump_release_opalcore,
+						0200, NULL,
+						fadump_release_opalcore_store);
+
 /* Init function for opalcore module. */
 static int __init opalcore_init(void)
 {
@@ -591,6 +623,12 @@ static int __init opalcore_init(void)
 		return rc;
 	}
 
+	rc = sysfs_create_file(kernel_kobj, &opalcore_rel_attr.attr);
+	if (rc) {
+		pr_warn("unable to create sysfs file fadump_release_opalcore (%d)\n",
+			rc);
+	}
+
 	return 0;
 }
 fs_initcall(opalcore_init);