Commit 17a801f4 authored by Chris Metcalf's avatar Chris Metcalf Committed by Linus Torvalds

list_debug: WARN for adding something already in the list

We were bitten by this at one point and added an additional sanity test
for DEBUG_LIST.  You can't validly add a list_head to a list where either
prev or next is the same as the thing you're adding.
Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 401dea7f
...@@ -31,6 +31,9 @@ void __list_add(struct list_head *new, ...@@ -31,6 +31,9 @@ void __list_add(struct list_head *new,
"list_add corruption. prev->next should be " "list_add corruption. prev->next should be "
"next (%p), but was %p. (prev=%p).\n", "next (%p), but was %p. (prev=%p).\n",
next, prev->next, prev); next, prev->next, prev);
WARN(new == prev || new == next,
"list_add double add: new=%p, prev=%p, next=%p.\n",
new, prev, next);
next->prev = new; next->prev = new;
new->next = next; new->next = next;
new->prev = prev; new->prev = prev;
......
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