liveupdate: auto unregister FLBs on file handler unregistration

To ensure that unregistration is always successful and doesn't leave
dangling resources, introduce auto-unregistration of FLBs: when a file
handler is unregistered, all FLBs associated with it are automatically
unregistered.

Introduce a new helper luo_flb_unregister_all() which unregisters all FLBs
linked to the given file handler.

Link: https://lore.kernel.org/20260327033335.696621-8-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c
index 97342b8b8b69dce60dfc71cb79df1e4b453b00be..9ba904c104250cba5457c50f861ec024f04639d1 100644 (file)
--- a/kernel/liveupdate/luo_file.c
+++ b/kernel/liveupdate/luo_file.c
@@ -923,26 +923,16 @@ err_unlock:
  */
 int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh)
 {
-       int err = -EBUSY;
-
        if (!liveupdate_enabled())
                return -EOPNOTSUPP;
 
        liveupdate_test_unregister(fh);
 
-       down_write(&luo_register_rwlock);
-       if (!list_empty(&ACCESS_PRIVATE(fh, flb_list)))
-               goto err_unlock;
-
+       guard(rwsem_write)(&luo_register_rwlock);
+       luo_flb_unregister_all(fh);
        list_del(&ACCESS_PRIVATE(fh, list));
-       up_write(&luo_register_rwlock);
 
        module_put(fh->ops->owner);
 
        return 0;
-
-err_unlock:
-       up_write(&luo_register_rwlock);
-       liveupdate_test_register(fh);
-       return err;
 }

diff --git a/kernel/liveupdate/luo_flb.c b/kernel/liveupdate/luo_flb.c
index 13f96d11ecc9a74d9c6a0960af1b9755e6ce160c..e069d694163ee5c4a227ae679cf90042b1048681 100644 (file)
--- a/kernel/liveupdate/luo_flb.c
+++ b/kernel/liveupdate/luo_flb.c
@@ -318,6 +318,62 @@ void luo_flb_file_finish(struct liveupdate_file_handler *fh)
                luo_flb_file_finish_one(iter->flb);
 }
 
+static void luo_flb_unregister_one(struct liveupdate_file_handler *fh,
+                                  struct liveupdate_flb *flb)
+{
+       struct luo_flb_private *private = luo_flb_get_private(flb);
+       struct list_head *flb_list = &ACCESS_PRIVATE(fh, flb_list);
+       struct luo_flb_link *iter;
+       bool found = false;
+
+       /* Find and remove the link from the file handler's list */
+       list_for_each_entry(iter, flb_list, list) {
+               if (iter->flb == flb) {
+                       list_del(&iter->list);
+                       kfree(iter);
+                       found = true;
+                       break;
+               }
+       }
+
+       if (!found) {
+               pr_warn("Failed to unregister FLB '%s': not found in file handler '%s'\n",
+                       flb->compatible, fh->compatible);
+               return;
+       }
+
+       private->users--;
+
+       /*
+        * If this is the last file-handler with which we are registred, remove
+        * from the global list.
+        */
+       if (!private->users) {
+               list_del_init(&private->list);
+               luo_flb_global.count--;
+       }
+}
+
+/**
+ * luo_flb_unregister_all - Unregister all FLBs associated with a file handler.
+ * @fh: The file handler whose FLBs should be unregistered.
+ *
+ * This function iterates through the list of FLBs associated with the given
+ * file handler and unregisters them all one by one.
+ */
+void luo_flb_unregister_all(struct liveupdate_file_handler *fh)
+{
+       struct list_head *flb_list = &ACCESS_PRIVATE(fh, flb_list);
+       struct luo_flb_link *iter, *tmp;
+
+       if (!liveupdate_enabled())
+               return;
+
+       lockdep_assert_held_write(&luo_register_rwlock);
+       list_for_each_entry_safe(iter, tmp, flb_list, list)
+               luo_flb_unregister_one(fh, iter->flb);
+}
+
 /**
  * liveupdate_register_flb - Associate an FLB with a file handler and register it globally.
  * @fh:   The file handler that will now depend on the FLB.
@@ -426,38 +482,12 @@ int liveupdate_register_flb(struct liveupdate_file_handler *fh,
 int liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
                              struct liveupdate_flb *flb)
 {
-       struct luo_flb_private *private = luo_flb_get_private(flb);
-       struct list_head *flb_list = &ACCESS_PRIVATE(fh, flb_list);
-       struct luo_flb_link *iter;
-       int err = -ENOENT;
-
        if (!liveupdate_enabled())
                return -EOPNOTSUPP;
 
        guard(rwsem_write)(&luo_register_rwlock);
 
-       /* Find and remove the link from the file handler's list */
-       list_for_each_entry(iter, flb_list, list) {
-               if (iter->flb == flb) {
-                       list_del(&iter->list);
-                       kfree(iter);
-                       err = 0;
-                       break;
-               }
-       }
-
-       if (err)
-               return err;
-
-       private->users--;
-       /*
-        * If this is the last file-handler with which we are registred, remove
-        * from the global list.
-        */
-       if (!private->users) {
-               list_del_init(&private->list);
-               luo_flb_global.count--;
-       }
+       luo_flb_unregister_one(fh, flb);
 
        return 0;
 }

diff --git a/kernel/liveupdate/luo_internal.h b/kernel/liveupdate/luo_internal.h
index 40a011bdfa55e74e0dbc954ab57fd0d0ea51246a..22f6901f89edc5e81137b599f247e27b0dc5a725 100644 (file)
--- a/kernel/liveupdate/luo_internal.h
+++ b/kernel/liveupdate/luo_internal.h
@@ -103,6 +103,7 @@ void luo_file_set_destroy(struct luo_file_set *file_set);
 int luo_flb_file_preserve(struct liveupdate_file_handler *fh);
 void luo_flb_file_unpreserve(struct liveupdate_file_handler *fh);
 void luo_flb_file_finish(struct liveupdate_file_handler *fh);
+void luo_flb_unregister_all(struct liveupdate_file_handler *fh);
 int __init luo_flb_setup_outgoing(void *fdt);
 int __init luo_flb_setup_incoming(void *fdt);
 void luo_flb_serialize(void);