From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: bpf@vger.kernel.org, netdev@vger.kernel.org
Cc: "Martin KaFai Lau" <kafai@fb.com>,
"Hangbin Liu" <liuhangbin@gmail.com>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
"Magnus Karlsson" <magnus.karlsson@gmail.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
"Jakub Kicinski" <kuba@kernel.org>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
"Madalin Bucur" <madalin.bucur@nxp.com>,
"Ioana Ciornei" <ioana.ciornei@nxp.com>,
"Ioana Radulescu" <ruxandra.radulescu@nxp.com>,
"Camelia Groza" <camelia.groza@nxp.com>
Subject: [PATCH bpf-next v4 10/19] freescale: remove rcu_read_lock() around XDP program invocation
Date: Wed, 23 Jun 2021 13:07:18 +0200 [thread overview]
Message-ID: <20210623110727.221922-11-toke@redhat.com> (raw)
In-Reply-To: <20210623110727.221922-1-toke@redhat.com>
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.
Cc: Madalin Bucur <madalin.bucur@nxp.com>
Cc: Ioana Ciornei <ioana.ciornei@nxp.com>
Cc: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Reviewed-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 8 +-------
drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c | 3 ---
2 files changed, 1 insertion(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
index 177c020bf34a..e6826561cf11 100644
--- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
+++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
@@ -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;
}
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 8433aa730c42..973352393bd4 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
@@ -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;
}
--
2.32.0
next prev parent reply other threads:[~2021-06-23 11:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-23 11:07 [PATCH bpf-next v4 00/19] Clean up and document RCU-based object protection for XDP and TC BPF Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 01/19] rcu: Create an unrcu_pointer() to remove __rcu from a pointer Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 02/19] doc: Clarify and expand RCU updaters and corresponding readers Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 03/19] doc: Give XDP as example of non-obvious RCU reader/updater pairing Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 04/19] bpf: allow RCU-protected lookups to happen from bh context Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 05/19] xdp: add proper __rcu annotations to redirect map entries Toke Høiland-Jørgensen
2021-06-24 13:12 ` Daniel Borkmann
2021-06-24 14:52 ` Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 06/19] sched: remove unneeded rcu_read_lock() around BPF program invocation Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 07/19] ena: remove rcu_read_lock() around XDP " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 08/19] bnxt: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 09/19] thunderx: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` Toke Høiland-Jørgensen [this message]
2021-06-23 11:07 ` [PATCH bpf-next v4 11/19] net: intel: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 12/19] marvell: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 13/19] mlx4: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 14/19] nfp: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 15/19] qede: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 16/19] sfc: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 17/19] netsec: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 18/19] stmmac: " Toke Høiland-Jørgensen
2021-06-23 11:07 ` [PATCH bpf-next v4 19/19] net: ti: " Toke Høiland-Jørgensen
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