diff options
| author | Toke Høiland-Jørgensen <toke@redhat.com> | 2021-06-24 18:06:06 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-06-24 19:46:01 +0200 |
| commit | 4eb14e3fc6197b7205069ed4e2b31eafa11a0697 (patch) | |
| tree | a31ac8a2c2aa564c0f4f781edbc83aeeff7ed2e9 /drivers/net/ethernet/sfc | |
| parent | 4415db6ca85ae57830a83290388f2b9dfa5f237f (diff) | |
sfc: Remove rcu_read_lock() around XDP program invocation
The sfc driver has rcu_read_lock()/rcu_read_unlock() pairs around XDP
program invocations. However, the actual lifetime of the objects referred
by the XDP program invocation is longer, all the way through to the call to
xdp_do_flush(), making the scope of the rcu_read_lock() too small. This
turns out to be harmless because it all happens in a single NAPI poll
cycle (and thus under local_bh_disable()), but it makes the rcu_read_lock()
misleading.
Rather than extend the scope of the rcu_read_lock(), just get rid of it
entirely. With the addition of RCU annotations to the XDP_REDIRECT map
types that take bh execution into account, lockdep even understands this to
be safe, so there's really no reason to keep it around.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Cc: Martin Habets <habetsm.xilinx@gmail.com>
Link: https://lore.kernel.org/bpf/20210624160609.292325-17-toke@redhat.com
Diffstat (limited to 'drivers/net/ethernet/sfc')
| -rw-r--r-- | drivers/net/ethernet/sfc/rx.c | 9 |
1 files changed, 2 insertions, 7 deletions
diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c index 17b8119c48e5..606750938b89 100644 --- a/drivers/net/ethernet/sfc/rx.c +++ b/drivers/net/ethernet/sfc/rx.c @@ -260,18 +260,14 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel, s16 offset; int err; - rcu_read_lock(); - xdp_prog = rcu_dereference(efx->xdp_prog); - if (!xdp_prog) { - rcu_read_unlock(); + xdp_prog = rcu_dereference_bh(efx->xdp_prog); + if (!xdp_prog) return true; - } rx_queue = efx_channel_get_rx_queue(channel); if (unlikely(channel->rx_pkt_n_frags > 1)) { /* We can't do XDP on fragmented packets - drop. */ - rcu_read_unlock(); efx_free_rx_buffers(rx_queue, rx_buf, channel->rx_pkt_n_frags); if (net_ratelimit()) @@ -296,7 +292,6 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel, rx_buf->len, false); xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp); - rcu_read_unlock(); offset = (u8 *)xdp.data - *ehp; |