linux/kernel/bpf
Yonghong Song 6c5f61023c bpf: fix rcu lockdep warning for lpm_trie map_free callback
Commit 9a3efb6b66 ("bpf: fix memory leak in lpm_trie map_free callback function")
fixed a memory leak and removed unnecessary locks in map_free callback function.
Unfortrunately, it introduced a lockdep warning. When lockdep checking is turned on,
running tools/testing/selftests/bpf/test_lpm_map will have:

  [   98.294321] =============================
  [   98.294807] WARNING: suspicious RCU usage
  [   98.295359] 4.16.0-rc2+ #193 Not tainted
  [   98.295907] -----------------------------
  [   98.296486] /home/yhs/work/bpf/kernel/bpf/lpm_trie.c:572 suspicious rcu_dereference_check() usage!
  [   98.297657]
  [   98.297657] other info that might help us debug this:
  [   98.297657]
  [   98.298663]
  [   98.298663] rcu_scheduler_active = 2, debug_locks = 1
  [   98.299536] 2 locks held by kworker/2:1/54:
  [   98.300152]  #0:  ((wq_completion)"events"){+.+.}, at: [<00000000196bc1f0>] process_one_work+0x157/0x5c0
  [   98.301381]  #1:  ((work_completion)(&map->work)){+.+.}, at: [<00000000196bc1f0>] process_one_work+0x157/0x5c0

Since actual trie tree removal happens only after no other
accesses to the tree are possible, replacing
  rcu_dereference_protected(*slot, lockdep_is_held(&trie->lock))
with
  rcu_dereference_protected(*slot, 1)
fixed the issue.

Fixes: 9a3efb6b66 ("bpf: fix memory leak in lpm_trie map_free callback function")
Reported-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-02-22 21:29:12 +01:00
..
arraymap.c bpf: add schedule points in percpu arrays management 2018-02-22 21:27:06 +01:00
bpf_lru_list.c bpf: lru: Lower the PERCPU_NR_SCANS from 16 to 4 2017-04-17 13:55:52 -04:00
bpf_lru_list.h bpf: Only set node->ref = 1 if it has not been set 2017-09-01 09:57:39 -07:00
cgroup.c bpf/cgroup: fix a verification error for a CGROUP_DEVICE type prog 2017-12-19 01:43:29 +01:00
core.c bpf: fix bpf_prog_array_copy_to_user warning from perf event prog query 2018-02-14 08:59:37 -08:00
cpumap.c bpf: cpumap: use GFP_KERNEL instead of GFP_ATOMIC in __cpu_map_entry_alloc() 2018-02-14 15:34:27 +01:00
devmap.c bpf: add helper for copying attrs to struct bpf_map 2018-01-14 23:36:29 +01:00
disasm.c bpf: allow for correlation of maps and helpers in dump 2017-12-20 18:09:40 -08:00
disasm.h bpf: annotate bpf_insn_print_t with __printf 2018-01-17 01:15:05 +01:00
hashtab.c bpf: add helper for copying attrs to struct bpf_map 2018-01-14 23:36:29 +01:00
helpers.c bpf: rename ARG_PTR_TO_STACK 2017-01-09 16:56:27 -05:00
inode.c Merge branch 'work.mqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 18:32:21 -08:00
lpm_trie.c bpf: fix rcu lockdep warning for lpm_trie map_free callback 2018-02-22 21:29:12 +01:00
Makefile bpf: only build sockmap with CONFIG_INET 2018-01-04 19:01:14 +01:00
map_in_map.c bpf: Add syscall lookup support for fd array and htab 2017-06-29 13:13:25 -04:00
map_in_map.h bpf: Add syscall lookup support for fd array and htab 2017-06-29 13:13:25 -04:00
offload.c bpf: offload: report device information about offloaded maps 2018-01-18 22:54:25 +01:00
percpu_freelist.c bpf: fix lockdep splat 2017-11-15 19:46:32 +09:00
percpu_freelist.h bpf: introduce percpu_freelist 2016-03-08 15:28:31 -05:00
sockmap.c bpf: fix sock_map_alloc() error path 2018-02-13 19:19:15 -08:00
stackmap.c bpf: add helper for copying attrs to struct bpf_map 2018-01-14 23:36:29 +01:00
syscall.c bpf: Use the IS_FD_ARRAY() macro in map_update_elem() 2018-01-25 18:05:24 -08:00
tnum.c bpf/verifier: track signed and unsigned min/max values 2017-08-08 17:51:34 -07:00
verifier.c bpf: fix subprog verifier bypass by div/mod by 0 exception 2018-01-26 16:42:05 -08:00