[PATCH v5 28/31] 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 <hbath...@linux.ibm.com>
---
 arch/powerpc/platforms/powernv/opal-core.c |   38 ++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/opal-core.c 
b/arch/powerpc/platforms/powernv/opal-core.c
index 2f1c8c1..a534f3d 100644
--- a/arch/powerpc/platforms/powernv/opal-core.c
+++ b/arch/powerpc/platforms/powernv/opal-core.c
@@ -15,6 +15,8 @@
 #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>
@@ -558,6 +560,36 @@ 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("'/sys/firmware/opal/core' file not 
accessible!\n");
+                       return -EPERM;
+               }
+
+               /*
+                * Take away '/sys/firmware/opal/core' 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)
 {
@@ -590,6 +622,12 @@ 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);