neighbor: Fix locking order for gc_list changes
Lock checker noted an inverted lock order between neigh_change_state (neighbor lock then table lock) and neigh_periodic_work (table lock and then neighbor lock) resulting in: [ 121.057652] ====================================================== [ 121.058740] WARNING: possible circular locking dependency detected [ 121.059861] 4.20.0-rc6+ #43 Not tainted [ 121.060546] ------------------------------------------------------ [ 121.061630] kworker/0:2/65 is trying to acquire lock: [ 121.062519] (____ptrval____) (&n->lock){++--}, at: neigh_periodic_work+0x237/0x324 [ 121.063894] [ 121.063894] but task is already holding lock: [ 121.064920] (____ptrval____) (&tbl->lock){+.-.}, at: neigh_periodic_work+0x194/0x324 [ 121.066274] [ 121.066274] which lock already depends on the new lock. [ 121.066274] [ 121.067693] [ 121.067693] the existing dependency chain (in reverse order) is: ... Fix by renaming neigh_change_state to neigh_update_gc_list, changing it to only manage whether an entry should be on the gc_list and taking locks in the same order as neigh_periodic_work. Invoke at the end of neigh_update only if diff between old or new states has the PERMANENT flag set. Fixes: 8cc196d6 ("neighbor: gc_list changes should be protected by table lock") Signed-off-by:David Ahern <dsahern@gmail.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
parent
aeb3fecd
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