[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 <hbath...@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);