• 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
nfp_net_common.c 85.2 KB