pstore: add pstore unregister

pstore doesn't support unregistering yet. It was marked as TODO.
This patch adds some code to fix it:
 1) Add functions to unregister kmsg/console/ftrace/pmsg.
 2) Add a function to free compression buffer.
 3) Unmap the memory and free it.
 4) Add a function to unregister pstore filesystem.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Acked-by: Kees Cook <keescook@chromium.org>
[Removed __exit annotation from ramoops_remove(). Reported by Arnd Bergmann]
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c
index 5a2f05a16c1e..7de20cd3797f 100644
--- a/fs/pstore/pmsg.c
+++ b/fs/pstore/pmsg.c
@@ -114,3 +114,10 @@ err_class:
 err:
 	return;
 }
+
+void pstore_unregister_pmsg(void)
+{
+	device_destroy(pmsg_class, MKDEV(pmsg_major, 0));
+	class_destroy(pmsg_class);
+	unregister_chrdev(pmsg_major, PMSG_NAME);
+}