From 49589b23d5a92dff4a7cb705608dff7dd13ef709 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Thu, 24 Jun 2021 18:06:01 +0200 Subject: [PATCH] intel: Remove rcu_read_lock() around XDP program invocation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The Intel drivers all 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 Tested-by: Jesper Dangaard Brouer # i40e Cc: Jesse Brandeburg Cc: Tony Nguyen Cc: intel-wired-lan@lists.osuosl.org Link: https://lore.kernel.org/bpf/20210624160609.292325-12-toke@redhat.com --- drivers/net/ethernet/intel/i40e/i40e_txrx.c | 2 -- drivers/net/ethernet/intel/i40e/i40e_xsk.c | 3 --- drivers/net/ethernet/intel/ice/ice_txrx.c | 6 +----- drivers/net/ethernet/intel/ice/ice_xsk.c | 3 --- drivers/net/ethernet/intel/igb/igb_main.c | 2 -- drivers/net/ethernet/intel/igc/igc_main.c | 7 ++----- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 -- drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 3 --- drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 2 -- 9 files changed, 3 insertions(+), 27 deletions(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c index b883ab809df30..38eb8151ee9a8 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c @@ -2298,7 +2298,6 @@ static int i40e_run_xdp(struct i40e_ring *rx_ring, struct xdp_buff *xdp) struct bpf_prog *xdp_prog; u32 act; - rcu_read_lock(); xdp_prog = READ_ONCE(rx_ring->xdp_prog); if (!xdp_prog) @@ -2334,7 +2333,6 @@ out_failure: break; } xdp_out: - rcu_read_unlock(); return result; } diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c index 68f177a86403f..e7e778ca074c0 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c @@ -153,7 +153,6 @@ static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, struct xdp_buff *xdp) struct bpf_prog *xdp_prog; u32 act; - rcu_read_lock(); /* NB! xdp_prog will always be !NULL, due to the fact that * this path is enabled by setting an XDP program. */ @@ -164,7 +163,6 @@ static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, struct xdp_buff *xdp) err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog); if (err) goto out_failure; - rcu_read_unlock(); return I40E_XDP_REDIR; } @@ -188,7 +186,6 @@ out_failure: result = I40E_XDP_CONSUMED; break; } - rcu_read_unlock(); return result; } diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c index 917eba7fdd0c4..dd791ca34faba 100644 --- a/drivers/net/ethernet/intel/ice/ice_txrx.c +++ b/drivers/net/ethernet/intel/ice/ice_txrx.c @@ -1135,15 +1135,11 @@ int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget) xdp.frame_sz = ice_rx_frame_truesize(rx_ring, size); #endif - rcu_read_lock(); xdp_prog = READ_ONCE(rx_ring->xdp_prog); - if (!xdp_prog) { - rcu_read_unlock(); + if (!xdp_prog) goto construct_skb; - } xdp_res = ice_run_xdp(rx_ring, &xdp, xdp_prog); - rcu_read_unlock(); if (!xdp_res) goto construct_skb; if (xdp_res & (ICE_XDP_TX | ICE_XDP_REDIR)) { diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c index 239b9bf107940..8a093368f6310 100644 --- a/drivers/net/ethernet/intel/ice/ice_xsk.c +++ b/drivers/net/ethernet/intel/ice/ice_xsk.c @@ -466,7 +466,6 @@ ice_run_xdp_zc(struct ice_ring *rx_ring, struct xdp_buff *xdp) struct ice_ring *xdp_ring; u32 act; - rcu_read_lock(); /* ZC patch is enabled only when XDP program is set, * so here it can not be NULL */ @@ -478,7 +477,6 @@ ice_run_xdp_zc(struct ice_ring *rx_ring, struct xdp_buff *xdp) err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog); if (err) goto out_failure; - rcu_read_unlock(); return ICE_XDP_REDIR; } @@ -503,7 +501,6 @@ out_failure: break; } - rcu_read_unlock(); return result; } diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index 5db303d64d147..7e6435dc7e80c 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -8381,7 +8381,6 @@ static struct sk_buff *igb_run_xdp(struct igb_adapter *adapter, struct bpf_prog *xdp_prog; u32 act; - rcu_read_lock(); xdp_prog = READ_ONCE(rx_ring->xdp_prog); if (!xdp_prog) @@ -8416,7 +8415,6 @@ out_failure: break; } xdp_out: - rcu_read_unlock(); return ERR_PTR(-result); } diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 3f6b6d4543a8e..95323095094dd 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -2240,18 +2240,15 @@ static struct sk_buff *igc_xdp_run_prog(struct igc_adapter *adapter, struct bpf_prog *prog; int res; - rcu_read_lock(); - prog = READ_ONCE(adapter->xdp_prog); if (!prog) { res = IGC_XDP_PASS; - goto unlock; + goto out; } res = __igc_xdp_run_prog(adapter, prog, xdp); -unlock: - rcu_read_unlock(); +out: return ERR_PTR(-res); } diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c index 2ac5b82676f3b..ffff69efd78a6 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -2199,7 +2199,6 @@ static struct sk_buff *ixgbe_run_xdp(struct ixgbe_adapter *adapter, struct xdp_frame *xdpf; u32 act; - rcu_read_lock(); xdp_prog = READ_ONCE(rx_ring->xdp_prog); if (!xdp_prog) @@ -2237,7 +2236,6 @@ out_failure: break; } xdp_out: - rcu_read_unlock(); return ERR_PTR(-result); } diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c index f72d2978263b9..96dd1a4f956a7 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c @@ -100,7 +100,6 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter, struct xdp_frame *xdpf; u32 act; - rcu_read_lock(); xdp_prog = READ_ONCE(rx_ring->xdp_prog); act = bpf_prog_run_xdp(xdp_prog, xdp); @@ -108,7 +107,6 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter, err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog); if (err) goto out_failure; - rcu_read_unlock(); return IXGBE_XDP_REDIR; } @@ -134,7 +132,6 @@ out_failure: result = IXGBE_XDP_CONSUMED; break; } - rcu_read_unlock(); return result; } diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c index dc56931fc1dcf..c714e1ecd3089 100644 --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c @@ -1054,7 +1054,6 @@ static struct sk_buff *ixgbevf_run_xdp(struct ixgbevf_adapter *adapter, struct bpf_prog *xdp_prog; u32 act; - rcu_read_lock(); xdp_prog = READ_ONCE(rx_ring->xdp_prog); if (!xdp_prog) @@ -1082,7 +1081,6 @@ out_failure: break; } xdp_out: - rcu_read_unlock(); return ERR_PTR(-result); } -- 2.30.2