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netsec: Remove rcu_read_lock() around XDP program invocation 

The netsec driver has a rcu_read_lock()/rcu_read_unlock() pair around the
full RX loop, covering everything up to and including xdp_do_flush(). This
is actually the correct behaviour, but because it all happens in a single
NAPI poll cycle (and thus under local_bh_disable()), it is also technically
redundant.

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 the rcu_read_lock() around anymore, so
let's just remove it.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Jassi Brar <jaswinder.singh@linaro.org>
Link: https://lore.kernel.org/bpf/20210624160609.292325-18-toke@redhat.com
This commit is contained in:
Toke Høiland-Jørgensen 2021-06-24 18:06:07 +02:00 committed by Daniel Borkmann
parent 4eb14e3fc6
commit 7b6ee873ff
1 changed files with 0 additions and 3 deletions
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3
drivers/net/ethernet/socionext/netsec.c
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@ -958,7 +958,6 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget)
xdp_init_buff(&xdp, PAGE_SIZE, &dring->xdp_rxq);
rcu_read_lock();
xdp_prog = READ_ONCE(priv->xdp_prog);
dma_dir = page_pool_get_dma_dir(dring->page_pool);
@ -1069,8 +1068,6 @@ next:
}
netsec_finalize_xdp_rx(priv, xdp_act, xdp_xmit);
rcu_read_unlock();
return done;
}