diff mbox series

[bpf-next,09/17] net: intel: remove rcu_read_lock() around XDP program invocation

Message ID 20210609103326.278782-10-toke@redhat.com
State New
Headers show
Series Clean up and document RCU-based object protection for XDP_REDIRECT | expand

Commit Message

Toke Høiland-Jørgensen June 9, 2021, 10:33 a.m. UTC 
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 <jesse.brandeburg@intel.com>
Cc: Tony Nguyen <anthony.l.nguyen@intel.com>
Cc: intel-wired-lan@lists.osuosl.org
Tested-by: Jesper Dangaard Brouer <brouer@redhat.com> # i40e
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 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 mbox series

Patch

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);
 }