[Skiboot] [PATCH] opal: use for_each_safe to iterate over opal_syncers

[Vaibhav Jain]

Presently a fault will happen in opal_sync_host_reboot if a callback
tries to remove itself from the opal_syncers list by calling
opal_del_host_sync_notifier.

This happens as iteration over opal_syncers is done using the
list_for_each() which doesn't preserve list_node->next. So when
the current opal_syncers callback removes itself from the list, current
node contents are lost and current_node->next pointer is rendered
invalid.

To fix this we simply switch from list_for_each() to
list_for_each_safe() which keeps the current_node->next cached hence
even if the current node is freed, iteration over subsequent nodes can
still continue.

Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
---
 core/opal.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/core/opal.c b/core/opal.c
index 7ffca9c1..63a08510 100644
--- a/core/opal.c
+++ b/core/opal.c
@@ -692,10 +692,10 @@ void opal_del_host_sync_notifier(bool (*notify)(void *data))
  */
 static int64_t opal_sync_host_reboot(void)
 {
-	struct opal_sync_entry *ent;
+	struct opal_sync_entry *ent, *nxt;
 	bool ret = true;
 
-	list_for_each(&opal_syncers, ent, link)
+	list_for_each_safe(&opal_syncers, ent, nxt, link)
 		ret &= ent->notify(ent->data);
 
 	if (ret)
-- 
2.17.1