diff options
| author | Toke Høiland-Jørgensen <toke@redhat.com> | 2021-06-24 18:06:08 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-06-24 19:46:25 +0200 |
| commit | 2f1e432d339c5fed435adf521cae392755721050 (patch) | |
| tree | 626683b2ed90859c4ac4edeb3153dd770aab2667 /drivers/net/ethernet/stmicro | |
| parent | 7b6ee873ff20c22af355661b241defa7f6ed7582 (diff) | |
stmmac: Remove rcu_read_lock() around XDP program invocation
The stmmac 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@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Jose Abreu <joabreu@synopsys.com>
Link: https://lore.kernel.org/bpf/20210624160609.292325-19-toke@redhat.com
Diffstat (limited to 'drivers/net/ethernet/stmicro')
| -rw-r--r-- | drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 16820873b01d..219535ab2c0c 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -4651,7 +4651,6 @@ static int stmmac_xdp_xmit_back(struct stmmac_priv *priv, return res; } -/* This function assumes rcu_read_lock() is held by the caller. */ static int __stmmac_xdp_run_prog(struct stmmac_priv *priv, struct bpf_prog *prog, struct xdp_buff *xdp) @@ -4693,17 +4692,14 @@ static struct sk_buff *stmmac_xdp_run_prog(struct stmmac_priv *priv, struct bpf_prog *prog; int res; - rcu_read_lock(); - prog = READ_ONCE(priv->xdp_prog); if (!prog) { res = STMMAC_XDP_PASS; - goto unlock; + goto out; } res = __stmmac_xdp_run_prog(priv, prog, xdp); -unlock: - rcu_read_unlock(); +out: return ERR_PTR(-res); } @@ -4973,10 +4969,8 @@ read_again: buf->xdp->data_end = buf->xdp->data + buf1_len; xsk_buff_dma_sync_for_cpu(buf->xdp, rx_q->xsk_pool); - rcu_read_lock(); prog = READ_ONCE(priv->xdp_prog); res = __stmmac_xdp_run_prog(priv, prog, buf->xdp); - rcu_read_unlock(); switch (res) { case STMMAC_XDP_PASS: |