From 959ad7ec066d9a61557ad6aedf77ea9b54c82df0 Mon Sep 17 00:00:00 2001 From: Toke Høiland-Jørgensen Date: Thu, 24 Jun 2021 18:06:02 +0200 Subject: marvell: Remove rcu_read_lock() around XDP program invocation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The mvneta and mvpp2 drivers have 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: Thomas Petazzoni Cc: Russell King Cc: Marcin Wojtas Link: https://lore.kernel.org/bpf/20210624160609.292325-13-toke@redhat.com --- drivers/net/ethernet/marvell/mvneta.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'drivers/net/ethernet/marvell/mvneta.c') diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c index c15ce06427d0..ada4e26a5492 100644 --- a/drivers/net/ethernet/marvell/mvneta.c +++ b/drivers/net/ethernet/marvell/mvneta.c @@ -2373,7 +2373,6 @@ static int mvneta_rx_swbm(struct napi_struct *napi, /* Get number of received packets */ rx_todo = mvneta_rxq_busy_desc_num_get(pp, rxq); - rcu_read_lock(); xdp_prog = READ_ONCE(pp->xdp_prog); /* Fairness NAPI loop */ @@ -2451,7 +2450,6 @@ next: xdp_buf.data_hard_start = NULL; sinfo.nr_frags = 0; } - rcu_read_unlock(); if (xdp_buf.data_hard_start) mvneta_xdp_put_buff(pp, rxq, &xdp_buf, &sinfo, -1); -- cgit