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nfp: Remove rcu_read_lock() around XDP program invocation
The nfp 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. While this is not actually an issue for the nfp driver because it doesn't support XDP_REDIRECT (and thus doesn't call xdp_do_flush()), the rcu_read_lock() is still unneeded. And 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> Reviewed-by: Simon Horman <simon.horman@netronome.com> Cc: oss-drivers@netronome.com Link: https://lore.kernel.org/bpf/20210624160609.292325-15-toke@redhat.com
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@ -1819,7 +1819,6 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, int budget)
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struct xdp_buff xdp;
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int idx;
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rcu_read_lock();
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xdp_prog = READ_ONCE(dp->xdp_prog);
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true_bufsz = xdp_prog ? PAGE_SIZE : dp->fl_bufsz;
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xdp_init_buff(&xdp, PAGE_SIZE - NFP_NET_RX_BUF_HEADROOM,
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@ -2036,7 +2035,6 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, int budget)
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if (!nfp_net_xdp_complete(tx_ring))
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pkts_polled = budget;
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}
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rcu_read_unlock();
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return pkts_polled;
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}
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