diff options
| author | Toke Høiland-Jørgensen <toke@redhat.com> | 2021-06-24 18:06:09 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-06-24 19:46:39 +0200 |
| commit | 0cc84b9a6003fa7f6ef5d19e7c8532a01cd41776 (patch) | |
| tree | 64460f00c0ded7b3f5141814faedc5c14ba7f63f | |
| parent | 2f1e432d339c5fed435adf521cae392755721050 (diff) | |
| download | linux-0cc84b9a6003fa7f6ef5d19e7c8532a01cd41776.tar.bz2 | |
ti: Remove rcu_read_lock() around XDP program invocation
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.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: linux-omap@vger.kernel.org
Link: https://lore.kernel.org/bpf/20210624160609.292325-20-toke@redhat.com
| -rw-r--r-- | drivers/net/ethernet/ti/cpsw_priv.c | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/drivers/net/ethernet/ti/cpsw_priv.c b/drivers/net/ethernet/ti/cpsw_priv.c index 5862f0a4a975..ecc2a6b7e28f 100644 --- a/drivers/net/ethernet/ti/cpsw_priv.c +++ b/drivers/net/ethernet/ti/cpsw_priv.c @@ -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; } |