Commit 547aabca authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Daniel Borkmann
Browse files

freescale: Remove rcu_read_lock() around XDP program invocation 



The dpaa and dpaa2 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: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarCamelia Groza <camelia.groza@nxp.com>
Cc: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Cc: Madalin Bucur <madalin.bucur@nxp.com>
Cc: Ioana Ciornei <ioana.ciornei@nxp.com>
Link: https://lore.kernel.org/bpf/20210624160609.292325-11-toke@redhat.com
parent 36baafe3

drivers/net/ethernet/freescale/dpaa/dpaa_eth.c

+1 −7
Original line number Diff line number Diff line
@@ -2558,13 +2558,9 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct qm_fd *fd, void *vaddr, 
	u32 xdp_act;

	int err;



	rcu_read_lock();



	xdp_prog = READ_ONCE(priv->xdp_prog);

	if (!xdp_prog) {

		rcu_read_unlock();

	if (!xdp_prog)

		return XDP_PASS;

	}



	xdp_init_buff(&xdp, DPAA_BP_RAW_SIZE - DPAA_TX_PRIV_DATA_SIZE,

		      &dpaa_fq->xdp_rxq);
@@ -2638,8 +2634,6 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct qm_fd *fd, void *vaddr, 
		break;

	}



	rcu_read_unlock();



	return xdp_act;

}

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c

+0 −3
Original line number Diff line number Diff line
@@ -352,8 +352,6 @@ static u32 dpaa2_eth_run_xdp(struct dpaa2_eth_priv *priv, 
	u32 xdp_act = XDP_PASS;

	int err, offset;



	rcu_read_lock();



	xdp_prog = READ_ONCE(ch->xdp.prog);

	if (!xdp_prog)

		goto out;
@@ -414,7 +412,6 @@ static u32 dpaa2_eth_run_xdp(struct dpaa2_eth_priv *priv, 


	ch->xdp.res |= xdp_act;

out:

	rcu_read_unlock();

	return xdp_act;

}