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  1. Dec 03, 2016
    • Daniel Borkmann's avatar
      bpf, xdp: drop rcu_read_lock from bpf_prog_run_xdp and move to caller · 366cbf2f
      Daniel Borkmann authored
      After 326fe02d ("net/mlx4_en: protect ring->xdp_prog with rcu_read_lock"),
      the rcu_read_lock() in bpf_prog_run_xdp() is superfluous, since callers
      need to hold rcu_read_lock() already to make sure BPF program doesn't
      get released in the background.
      
      Thus, drop it from bpf_prog_run_xdp(), as it can otherwise be misleading.
      Still keeping the bpf_prog_run_xdp() is useful as it allows for grepping
      in XDP supported drivers and to keep the typecheck on the context intact.
      For mlx4, this means we don't have a double rcu_read_lock() anymore. nfp can
      just make use of bpf_prog_run_xdp(), too. For qede, just move rcu_read_lock()
      out of the helper. When the driver gets atomic replace support, this will
      move to call-sites eventually.
      
      mlx5 needs actual fixing as it has the same issue as described already in
      326fe02d ("net/mlx4_en: protect ring->xdp_prog with rcu_read_lock"),
      that is, we're under RCU bh at this time, BPF programs are released via
      call_rcu(), and call_rcu() != call_rcu_bh(), so we need to properly mark
      read side as programs can get xchg()'ed in mlx5e_xdp_set() without queue
      reset.
      
      Fixes: 86994156
      
       ("net/mlx5e: XDP fast RX drop bpf programs support")
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Acked-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      366cbf2f
  2. Dec 02, 2016
  3. Dec 01, 2016