From: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
The i40e 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.
Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
---
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 2 --
drivers/net/ethernet/intel/i40e/i40e_xsk.c | 6 +-----
2 files changed, 1 insertion(+), 7 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index fc20afc23bfa..3f4c947a5185 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -2303,7 +2303,6 @@ static struct sk_buff *i40e_run_xdp(struct i40e_ring *rx_ring,
struct bpf_prog *xdp_prog;
u32 act;
- rcu_read_lock();
xdp_prog = READ_ONCE(rx_ring->xdp_prog);
if (!xdp_prog)
@@ -2334,7 +2333,6 @@ static struct sk_buff *i40e_run_xdp(struct i40e_ring *rx_ring,
break;
}
xdp_out:
- rcu_read_unlock();
return ERR_PTR(-result);
}
diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index d89c22347d9d..93b349f11d3b 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;
}
