kernel/linux.git/drivers/net/loopback.c, branch v6.1.2

net: loopback: use NET_NAME_PREDICTABLE for name_assign_type

2022-11-25T09:39:05+00:00

When the name_assign_type attribute was introduced (commit 685343fc3ba6, "net: add name_assign_type netdev attribute"), the loopback device was explicitly mentioned as one which would make use of NET_NAME_PREDICTABLE: The name_assign_type attribute gives hints where the interface name of a given net-device comes from. These values are currently defined: ... NET_NAME_PREDICTABLE: The ifname has been assigned by the kernel in a predictable way that is guaranteed to avoid reuse and always be the same for a given device. Examples include statically created devices like the loopback device [...] Switch to that so that reading /sys/class/net/lo/name_assign_type produces something sensible instead of returning -EINVAL. Signed-off-by: Rasmus Villemoes Reviewed-by: Jacob Keller Signed-off-by: David S. Miller

net: loopback: enable BIG TCP packets

2022-05-16T09:18:56+00:00

Set the driver limit to GSO_MAX_SIZE (512 KB). This allows the admin/user to set a GSO limit up to this value. Tested: ip link set dev lo gso_max_size 200000 netperf -H ::1 -t TCP_RR -l 100 -- -r 80000,80000 & tcpdump shows : 18:28:42.962116 IP6 ::1 > ::1: HBH 40051 > 63780: Flags [P.], seq 3626480001:3626560001, ack 3626560001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 80000 18:28:42.962138 IP6 ::1.63780 > ::1.40051: Flags [.], ack 3626560001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 0 18:28:42.962152 IP6 ::1 > ::1: HBH 63780 > 40051: Flags [P.], seq 3626560001:3626640001, ack 3626560001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 80000 18:28:42.962157 IP6 ::1.40051 > ::1.63780: Flags [.], ack 3626640001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 0 18:28:42.962180 IP6 ::1 > ::1: HBH 40051 > 63780: Flags [P.], seq 3626560001:3626640001, ack 3626640001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 80000 18:28:42.962214 IP6 ::1.63780 > ::1.40051: Flags [.], ack 3626640001, win 17743, options [nop,nop,TS val 3771179266 ecr 3771179265], length 0 18:28:42.962228 IP6 ::1 > ::1: HBH 63780 > 40051: Flags [P.], seq 3626640001:3626720001, ack 3626640001, win 17743, options [nop,nop,TS val 3771179266 ecr 3771179265], length 80000 18:28:42.962233 IP6 ::1.40051 > ::1.63780: Flags [.], ack 3626720001, win 17743, options [nop,nop,TS val 3771179266 ecr 3771179266], length 0 Signed-off-by: Eric Dumazet Acked-by: Alexander Duyck Signed-off-by: David S. Miller

net: Add skb_clear_tstamp() to keep the mono delivery_time

2022-03-03T14:38:48+00:00

Right now, skb->tstamp is reset to 0 whenever the skb is forwarded. If skb->tstamp has the mono delivery_time, clearing it can hurt the performance when it finally transmits out to fq@phy-dev. The earlier patch added a skb->mono_delivery_time bit to flag the skb->tstamp carrying the mono delivery_time. This patch adds skb_clear_tstamp() helper which keeps the mono delivery_time and clears everything else. The delivery_time clearing will be postponed until the stack knows the skb will be delivered locally. It will be done in a latter patch. Signed-off-by: Martin KaFai Lau Signed-off-by: David S. Miller

net: dev: Makes sure netif_rx() can be invoked in any context.

2022-02-14T13:38:35+00:00

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 Reviewed-by: Eric Dumazet Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller

net: Don't include filter.h from net/sock.h

2021-12-29T16:48:14+00:00

sock.h is pretty heavily used (5k objects rebuilt on x86 after it's touched). We can drop the include of filter.h from it and add a forward declaration of struct sk_filter instead. This decreases the number of rebuilt objects when bpf.h is touched from ~5k to ~1k. There's a lot of missing includes this was masking. Primarily in networking tho, this time. Signed-off-by: Jakub Kicinski Signed-off-by: Alexei Starovoitov Acked-by: Marc Kleine-Budde Acked-by: Florian Fainelli Acked-by: Nikolay Aleksandrov Acked-by: Stefano Garzarella Link: https://lore.kernel.org/bpf/20211229004913.513372-1-kuba@kernel.org

net: use u64_stats_t in struct pcpu_lstats

2019-11-08T04:03:08+00:00

In order to fix the data-race found by KCSAN, we can use the new u64_stats_t type and its accessors instead of plain u64 fields. This will still generate optimal code for both 32 and 64 bit platforms. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: provide dev_lstats_add() helper

2019-11-08T04:03:08+00:00

Many network drivers need it and hand-coded the same function. In order to ease u64_stats_t adoption, it is time to factorize. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: provide dev_lstats_read() helper

2019-11-08T04:03:08+00:00

Many network drivers use hand-coded implementation of the same thing, let's factorize things so that u64_stats_t adoption is done once. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

loopback: fix lockdep splat

2019-07-03T18:24:38+00:00

dev_init_scheduler() and dev_activate() expect the caller to hold RTNL. Since we don't want blackhole device to be initialized per ns, we are initializing at init. [ 3.855027] Call Trace: [ 3.855034] dump_stack+0x67/0x95 [ 3.855037] lockdep_rcu_suspicious+0xd5/0x110 [ 3.855044] dev_init_scheduler+0xe3/0x120 [ 3.855048] ? net_olddevs_init+0x60/0x60 [ 3.855050] blackhole_netdev_init+0x45/0x6e [ 3.855052] do_one_initcall+0x6c/0x2fa [ 3.855058] ? rcu_read_lock_sched_held+0x8c/0xa0 [ 3.855066] kernel_init_freeable+0x1e5/0x288 [ 3.855071] ? rest_init+0x260/0x260 [ 3.855074] kernel_init+0xf/0x180 [ 3.855076] ? rest_init+0x260/0x260 [ 3.855078] ret_from_fork+0x24/0x30 Fixes: 4de83b88c66 ("loopback: create blackhole net device similar to loopack.") Reported-by: Geert Uytterhoeven Cc: Eric Dumazet Signed-off-by: Mahesh Bandewar Tested-by: Geert Uytterhoeven Signed-off-by: David S. Miller

loopback: create blackhole net device similar to loopack.

2019-07-02T02:34:46+00:00

Create a blackhole net device that can be used for "dead" dst entries instead of loopback device. This blackhole device differs from loopback in few aspects: (a) It's not per-ns. (b) MTU on this device is ETH_MIN_MTU (c) The xmit function is essentially kfree_skb(). and (d) since it's not registered it won't have ifindex. Lower MTU effectively make the device not pass the MTU check during the route check when a dst associated with the skb is dead. Signed-off-by: Mahesh Bandewar Signed-off-by: David S. Miller