diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2022-02-12 02:38:38 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2022-02-14 16:38:35 +0300 |
| commit | baebdf48c360080710f80699eea3affbb13d6c65 (patch) | |
| tree | 1d29aa72815907a13fd9cfc43115a91f249c5d80 /drivers/net/ntb_netdev.c | |
| parent | f234ae2947612825686b25cae3e9579188a6ba95 (diff) | |
| download | linux-baebdf48c360080710f80699eea3affbb13d6c65.tar.xz | |
net: dev: Makes sure netif_rx() can be invoked in any context.
Dave suggested a while ago (eleven years by now) "Let's make netif_rx()
work in all contexts and get rid of netif_rx_ni()". Eric agreed and
pointed out that modern devices should use netif_receive_skb() to avoid
the overhead.
In the meantime someone added another variant, netif_rx_any_context(),
which behaves as suggested.
netif_rx() must be invoked with disabled bottom halves to ensure that
pending softirqs, which were raised within the function, are handled.
netif_rx_ni() can be invoked only from process context (bottom halves
must be enabled) because the function handles pending softirqs without
checking if bottom halves were disabled or not.
netif_rx_any_context() invokes on the former functions by checking
in_interrupts().
netif_rx() could be taught to handle both cases (disabled and enabled
bottom halves) by simply disabling bottom halves while invoking
netif_rx_internal(). The local_bh_enable() invocation will then invoke
pending softirqs only if the BH-disable counter drops to zero.
Eric is concerned about the overhead of BH-disable+enable especially in
regard to the loopback driver. As critical as this driver is, it will
receive a shortcut to avoid the additional overhead which is not needed.
Add a local_bh_disable() section in netif_rx() to ensure softirqs are
handled if needed.
Provide __netif_rx() which does not disable BH and has a lockdep assert
to ensure that interrupts are disabled. Use this shortcut in the
loopback driver and in drivers/net/*.c.
Make netif_rx_ni() and netif_rx_any_context() invoke netif_rx() so they
can be removed once they are no more users left.
Link: https://lkml.kernel.org/r/20100415.020246.218622820.davem@davemloft.net
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ntb_netdev.c')
| -rw-r--r-- | drivers/net/ntb_netdev.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/ntb_netdev.c b/drivers/net/ntb_netdev.c index 98ca6b18415e..80bdc07f2cd3 100644 --- a/drivers/net/ntb_netdev.c +++ b/drivers/net/ntb_netdev.c @@ -119,7 +119,7 @@ static void ntb_netdev_rx_handler(struct ntb_transport_qp *qp, void *qp_data, skb->protocol = eth_type_trans(skb, ndev); skb->ip_summed = CHECKSUM_NONE; - if (netif_rx(skb) == NET_RX_DROP) { + if (__netif_rx(skb) == NET_RX_DROP) { ndev->stats.rx_errors++; ndev->stats.rx_dropped++; } else { |