@@ -1328,13 +1328,9 @@ int cpsw_run_xdp(struct cpsw_priv *priv, int ch, struct xdp_buff *xdp,
struct bpf_prog *prog;
u32 act;
- rcu_read_lock();
-
prog = READ_ONCE(priv->xdp_prog);
- if (!prog) {
- ret = CPSW_XDP_PASS;
- goto out;
- }
+ if (!prog)
+ return CPSW_XDP_PASS;
act = bpf_prog_run_xdp(prog, xdp);
/* XDP prog might have changed packet data and boundaries */
@@ -1378,10 +1374,8 @@ int cpsw_run_xdp(struct cpsw_priv *priv, int ch, struct xdp_buff *xdp,
ndev->stats.rx_bytes += *len;
ndev->stats.rx_packets++;
out:
- rcu_read_unlock();
return ret;
drop:
- rcu_read_unlock();
page_pool_recycle_direct(cpsw->page_pool[ch], page);
return ret;
}
The cpsw driver has 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: Grygorii Strashko <grygorii.strashko@ti.com> Cc: linux-omap@vger.kernel.org Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> --- drivers/net/ethernet/ti/cpsw_priv.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)