From: Toke Høiland-Jørgensen Date: Thu, 24 Jun 2021 16:06:05 +0000 (+0200) Subject: qede: Remove rcu_read_lock() around XDP program invocation X-Git-Tag: v5.15~843^2~14^2~9 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4415db6ca85ae57830a83290388f2b9dfa5f237f;p=platform%2Fkernel%2Flinux-starfive.git 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 Signed-off-by: Daniel Borkmann Cc: Ariel Elior Cc: gr-everest-linux-l2@marvell.com Link: https://lore.kernel.org/bpf/20210624160609.292325-16-toke@redhat.com --- diff --git a/drivers/net/ethernet/qlogic/qede/qede_fp.c b/drivers/net/ethernet/qlogic/qede/qede_fp.c index 8e150dd..065e900 100644 --- a/drivers/net/ethernet/qlogic/qede/qede_fp.c +++ b/drivers/net/ethernet/qlogic/qede/qede_fp.c @@ -1089,13 +1089,7 @@ static bool qede_rx_xdp(struct qede_dev *edev, xdp_prepare_buff(&xdp, page_address(bd->data), *data_offset, *len, false); - /* Queues always have a full reset currently, so for the time - * being until there's atomic program replace just mark read - * side for map helpers. - */ - rcu_read_lock(); act = bpf_prog_run_xdp(prog, &xdp); - rcu_read_unlock(); /* Recalculate, as XDP might have changed the headers */ *data_offset = xdp.data - xdp.data_hard_start;