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qede: Remove rcu_read_lock() around XDP program invocation
The qede 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> Cc: Ariel Elior <aelior@marvell.com> Cc: gr-everest-linux-l2@marvell.com Link: https://lore.kernel.org/bpf/20210624160609.292325-16-toke@redhat.com
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1 changed files with 0 additions and 6 deletions
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@ -1089,13 +1089,7 @@ static bool qede_rx_xdp(struct qede_dev *edev,
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xdp_prepare_buff(&xdp, page_address(bd->data), *data_offset,
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xdp_prepare_buff(&xdp, page_address(bd->data), *data_offset,
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*len, false);
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*len, false);
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/* Queues always have a full reset currently, so for the time
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* being until there's atomic program replace just mark read
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* side for map helpers.
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*/
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rcu_read_lock();
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act = bpf_prog_run_xdp(prog, &xdp);
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act = bpf_prog_run_xdp(prog, &xdp);
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rcu_read_unlock();
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/* Recalculate, as XDP might have changed the headers */
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/* Recalculate, as XDP might have changed the headers */
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*data_offset = xdp.data - xdp.data_hard_start;
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*data_offset = xdp.data - xdp.data_hard_start;
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