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McKenney" , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , Jesse Brandeburg , Tony Nguyen , intel-wired-lan@lists.osuosl.org Subject: [PATCH bpf-next 09/17] net: intel: remove rcu_read_lock() around XDP program invocation Date: Wed, 9 Jun 2021 12:33:18 +0200 Message-Id: <20210609103326.278782-10-toke@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210609103326.278782-1-toke@redhat.com> References: <20210609103326.278782-1-toke@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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. Cc: Jesse Brandeburg Cc: Tony Nguyen Cc: intel-wired-lan@lists.osuosl.org Tested-by: Jesper Dangaard Brouer # i40e Signed-off-by: Toke Høiland-Jørgensen --- drivers/net/ethernet/intel/i40e/i40e_txrx.c | 2 -- drivers/net/ethernet/intel/i40e/i40e_xsk.c | 6 +----- drivers/net/ethernet/intel/ice/ice_txrx.c | 6 +----- drivers/net/ethernet/intel/ice/ice_xsk.c | 6 +----- 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 | 6 +----- drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 2 -- 9 files changed, 6 insertions(+), 33 deletions(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c index de70c16ef619..ae3a64b6f5f8 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) @@ -2329,7 +2328,6 @@ static int i40e_run_xdp(struct i40e_ring *rx_ring, struct xdp_buff *xdp) 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 46d884417c63..8dca53b7daff 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. */ @@ -162,9 +161,7 @@ static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, struct xdp_buff *xdp) if (likely(act == XDP_REDIRECT)) { err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog); - result = !err ? I40E_XDP_REDIR : I40E_XDP_CONSUMED; - rcu_read_unlock(); - return result; + return !err ? I40E_XDP_REDIR : I40E_XDP_CONSUMED; } switch (act) { @@ -184,7 +181,6 @@ static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, struct xdp_buff *xdp) 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 e2b4b29ea207..1a311e91fb6d 100644 --- a/drivers/net/ethernet/intel/ice/ice_txrx.c +++ b/drivers/net/ethernet/intel/ice/ice_txrx.c @@ -1129,15 +1129,11 @@ 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 faa7b8d96adb..d6da377f5ac3 100644 --- a/drivers/net/ethernet/intel/ice/ice_xsk.c +++ b/drivers/net/ethernet/intel/ice/ice_xsk.c @@ -463,7 +463,6 @@ 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 */ @@ -473,9 +472,7 @@ ice_run_xdp_zc(struct ice_ring *rx_ring, struct xdp_buff *xdp) if (likely(act == XDP_REDIRECT)) { err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog); - result = !err ? ICE_XDP_REDIR : ICE_XDP_CONSUMED; - rcu_read_unlock(); - return result; + return !err ? ICE_XDP_REDIR : ICE_XDP_CONSUMED; } switch (act) { @@ -496,7 +493,6 @@ ice_run_xdp_zc(struct ice_ring *rx_ring, struct xdp_buff *xdp) 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 038a9fd1af44..8a11b7e55326 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -8387,7 +8387,6 @@ 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) @@ -8420,7 +8419,6 @@ static struct sk_buff *igb_run_xdp(struct igb_adapter *adapter, 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 ea998d2defa4..2b666a6ec989 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -2175,18 +2175,15 @@ 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 c5ec17d19c59..27d7467534e0 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 @@ static struct sk_buff *ixgbe_run_xdp(struct ixgbe_adapter *adapter, 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 91ad5b902673..ffbf8a694362 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c @@ -100,15 +100,12 @@ 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); if (likely(act == XDP_REDIRECT)) { err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog); - result = !err ? IXGBE_XDP_REDIR : IXGBE_XDP_CONSUMED; - rcu_read_unlock(); - return result; + return !err ? IXGBE_XDP_REDIR : IXGBE_XDP_CONSUMED; } switch (act) { @@ -132,7 +129,6 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter, 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 ba2ed8a43d2d..fabada4ce315 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) @@ -1079,7 +1078,6 @@ static struct sk_buff *ixgbevf_run_xdp(struct ixgbevf_adapter *adapter, break; } xdp_out: - rcu_read_unlock(); return ERR_PTR(-result); }