Commit f4846e52 authored Mar 14, 2013 by Linus Torvalds

linux-rcu

Pull fix for hlist_entry_safe() regression from Paul McKenney:
 "This contains a single commit that fixes a regression in
  hlist_entry_safe().  This macro references its argument twice, which
  can cause NULL-pointer errors.  This commit applies a gcc statement
  expression, creating a temporary variable to avoid the double
  reference.  This has been posted to LKML at

    https://lkml.org/lkml/2013/3/9/75.

  Kudos to CAI Qian, whose testing uncovered this, to Eric Dumazet, who
  spotted root cause, and to Li Zefan, who tested this commit."

* 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  list: Fix double fetch of pointer in hlist_entry_safe()

parents 40e4591d f65846a1

include/linux/list.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -667,7 +667,9 @@ static inline void hlist_move_list(struct hlist_head *old,
		pos = n)

		#define hlist_entry_safe(ptr, type, member) \
		(ptr) ? hlist_entry(ptr, type, member) : NULL
		({ typeof(ptr) ____ptr = (ptr); \
		____ptr ? hlist_entry(____ptr, type, member) : NULL; \
		})

		/**
		* hlist_for_each_entry - iterate over list of given type