mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
sfc: Remove rcu_read_lock() around XDP program invocation
The sfc 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> Acked-by: Edward Cree <ecree.xilinx@gmail.com> Cc: Martin Habets <habetsm.xilinx@gmail.com> Link: https://lore.kernel.org/bpf/20210624160609.292325-17-toke@redhat.com
This commit is contained in:
parent
4415db6ca8
commit
4eb14e3fc6
1 changed files with 2 additions and 7 deletions
|
@ -260,18 +260,14 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
|
|||
s16 offset;
|
||||
int err;
|
||||
|
||||
rcu_read_lock();
|
||||
xdp_prog = rcu_dereference(efx->xdp_prog);
|
||||
if (!xdp_prog) {
|
||||
rcu_read_unlock();
|
||||
xdp_prog = rcu_dereference_bh(efx->xdp_prog);
|
||||
if (!xdp_prog)
|
||||
return true;
|
||||
}
|
||||
|
||||
rx_queue = efx_channel_get_rx_queue(channel);
|
||||
|
||||
if (unlikely(channel->rx_pkt_n_frags > 1)) {
|
||||
/* We can't do XDP on fragmented packets - drop. */
|
||||
rcu_read_unlock();
|
||||
efx_free_rx_buffers(rx_queue, rx_buf,
|
||||
channel->rx_pkt_n_frags);
|
||||
if (net_ratelimit())
|
||||
|
@ -296,7 +292,6 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
|
|||
rx_buf->len, false);
|
||||
|
||||
xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);
|
||||
rcu_read_unlock();
|
||||
|
||||
offset = (u8 *)xdp.data - *ehp;
|
||||
|
||||
|
|
Loading…
Reference in a new issue