The per-CPU variables used during bpf_prog_run_xdp() invocation and
later during xdp_do_redirect() rely on disabled BH for their protection.
Without locking in local_bh_disable() on PREEMPT_RT these data structure
require explicit locking.
This is a follow-up on the previous change which introduced
bpf_run_lock.redirect_lock and uses it now within drivers.
The simple way is to acquire the lock before bpf_prog_run_xdp() is
invoked and hold it until the end of function.
This does not always work because some drivers (cpsw, atlantic) invoke
xdp_do_flush() in the same context.
Acquiring the lock in bpf_prog_run_xdp() and dropping in
xdp_do_redirect() (without touching drivers) does not work because not
all driver, which use bpf_prog_run_xdp(), do support XDP_REDIRECT (and
invoke xdp_do_redirect()).
Ideally the minimal locking scope would be bpf_prog_run_xdp() +
xdp_do_redirect() and everything else (error recovery, DMA unmapping,
free/ alloc of memory, …) would happen outside of the locked section.
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Clark Wang <xiaoning.wang@xxxxxxx>
Cc: Claudiu Manoil <claudiu.manoil@xxxxxxx>
Cc: Ioana Ciornei <ioana.ciornei@xxxxxxx>
Cc: Jesper Dangaard Brouer <hawk@xxxxxxxxxx>
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: Madalin Bucur <madalin.bucur@xxxxxxx>
Cc: NXP Linux Team <linux-imx@xxxxxxx>
Cc: Shenwei Wang <shenwei.wang@xxxxxxx>
Cc: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Cc: Wei Fang <wei.fang@xxxxxxx>
Cc: bpf@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
.../net/ethernet/freescale/dpaa/dpaa_eth.c | 1 +
.../net/ethernet/freescale/dpaa2/dpaa2-eth.c | 1 +
.../net/ethernet/freescale/dpaa2/dpaa2-xsk.c | 30 ++++++++++---------
drivers/net/ethernet/freescale/enetc/enetc.c | 1 +
drivers/net/ethernet/freescale/fec_main.c | 1 +
5 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
index dcbc598b11c6c..8adc766282fde 100644
--- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
+++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
@@ -2597,6 +2597,7 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct qm_fd *fd, void *vaddr,
}
#endif
+ guard(local_lock_nested_bh)(&bpf_run_lock.redirect_lock);
xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);
/* Update the length and the offset of the FD */
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 888509cf1f210..08be35a3e3de7 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
@@ -442,6 +442,7 @@ static u32 dpaa2_eth_run_xdp(struct dpaa2_eth_priv *priv,
xdp_prepare_buff(&xdp, vaddr + offset, XDP_PACKET_HEADROOM,
dpaa2_fd_get_len(fd), false);
+ guard(local_lock_nested_bh)(&bpf_run_lock.redirect_lock);
xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);
/* xdp.data pointer may have changed */
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c
index 051748b997f3f..e3ae9de6b0a34 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c
@@ -56,23 +56,25 @@ static u32 dpaa2_xsk_run_xdp(struct dpaa2_eth_priv *priv,
xdp_buff->rxq = &ch->xdp_rxq;
xsk_buff_dma_sync_for_cpu(xdp_buff, ch->xsk_pool);
- xdp_act = bpf_prog_run_xdp(xdp_prog, xdp_buff);
+ scoped_guard(local_lock_nested_bh, &bpf_run_lock.redirect_lock) {
+ xdp_act = bpf_prog_run_xdp(xdp_prog, xdp_buff);
- /* xdp.data pointer may have changed */
- dpaa2_fd_set_offset(fd, xdp_buff->data - vaddr);
- dpaa2_fd_set_len(fd, xdp_buff->data_end - xdp_buff->data);
+ /* xdp.data pointer may have changed */
+ dpaa2_fd_set_offset(fd, xdp_buff->data - vaddr);
+ dpaa2_fd_set_len(fd, xdp_buff->data_end - xdp_buff->data);
- if (likely(xdp_act == XDP_REDIRECT)) {
- err = xdp_do_redirect(priv->net_dev, xdp_buff, xdp_prog);
- if (unlikely(err)) {
- ch->stats.xdp_drop++;
- dpaa2_eth_recycle_buf(priv, ch, addr);
- } else {
- ch->buf_count--;
- ch->stats.xdp_redirect++;
+ if (likely(xdp_act == XDP_REDIRECT)) {
+ err = xdp_do_redirect(priv->net_dev, xdp_buff, xdp_prog);
+ if (unlikely(err)) {
+ ch->stats.xdp_drop++;
+ dpaa2_eth_recycle_buf(priv, ch, addr);
+ } else {
+ ch->buf_count--;
+ ch->stats.xdp_redirect++;
+ }
+
+ goto xdp_redir;
}
-
- goto xdp_redir;
}
switch (xdp_act) {
diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index cffbf27c4656b..d516b28815af4 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c
@@ -1578,6 +1578,7 @@ static int enetc_clean_rx_ring_xdp(struct enetc_bdr *rx_ring,
rx_byte_cnt += VLAN_HLEN;
rx_byte_cnt += xdp_get_buff_len(&xdp_buff);
+ guard(local_lock_nested_bh)(&bpf_run_lock.redirect_lock);
xdp_act = bpf_prog_run_xdp(prog, &xdp_buff);
switch (xdp_act) {
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index c3b7694a74851..335b1e307d468 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1587,6 +1587,7 @@ fec_enet_run_xdp(struct fec_enet_private *fep, struct bpf_prog *prog,
int err;
u32 act;
+ guard(local_lock_nested_bh)(&bpf_run_lock.redirect_lock);
act = bpf_prog_run_xdp(prog, xdp);
/* Due xdp_adjust_tail and xdp_adjust_head: DMA sync for_device cover
--
2.43.0
