While playing with mlx4 hardware timestamping of RX packets, I found
that some packets were received by TCP stack with a ~200 ms delay...
Since the timestamp was provided by the NIC, and my probe was added
in tcp_v4_rcv() while in BH handler, I was confident it was not
a sender issue, or a drop in the network.
This would happen with a very low probability, but hurting RPC
workloads.
A NAPI driver normally arms the IRQ after the napi_complete_done(),
after NAPI_STATE_SCHED is cleared, so that the hard irq handler can grab
it.
Problem is that if another point in the stack grabs NAPI_STATE_SCHED bit
while IRQ are not disabled, we might have later an IRQ firing and
finding this bit set, right before napi_complete_done() clears it.
This can happen with busy polling users, or if gro_flush_timeout is
used. But some other uses of napi_schedule() in drivers can cause this
as well.
thread 1 thread 2 (could be on same cpu, or not)
// busy polling or napi_watchdog()
napi_schedule();
...
napi->poll()
device polling:
read 2 packets from ring buffer
Additional 3rd packet is
available.
device hard irq
// does nothing because
NAPI_STATE_SCHED bit is owned by thread 1
napi_schedule();
napi_complete_done(napi, 2);
rearm_irq();
Note that rearm_irq() will not force the device to send an additional
IRQ for the packet it already signaled (3rd packet in my example)
This patch adds a new NAPI_STATE_MISSED bit, that napi_schedule_prep()
can set if it could not grab NAPI_STATE_SCHED
Then napi_complete_done() properly reschedules the napi to make sure
we do not miss something.
Since we manipulate multiple bits at once, use cmpxchg() like in
sk_busy_loop() to provide proper transactions.
In v2, I changed napi_watchdog() to use a relaxed variant of
napi_schedule_prep() : No need to set NAPI_STATE_MISSED from this point.
In v3, I added more details in the changelog and clears
NAPI_STATE_MISSED in busy_poll_stop()
In v4, I added the ideas given by Alexander Duyck in v3 review
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Steffen Klassert says:
====================
pull request (net-next): ipsec-next 2017-02-16
1) Make struct xfrm_input_afinfo const, nothing writes to it.
From Florian Westphal.
2) Remove all places that write to the afinfo policy backend
and make the struct const then.
From Florian Westphal.
3) Prepare for packet consuming gro callbacks and add
ESP GRO handlers. ESP packets can be decapsulated
at the GRO layer then. It saves a round through
the stack for each ESP packet.
Please note that this has a merge coflict between commit
63fca65d0863 ("net: add confirm_neigh method to dst_ops")
from net-next and
3d7d25a68ea5 ("xfrm: policy: remove garbage_collect callback")
a2817d8b279b ("xfrm: policy: remove family field")
from ipsec-next.
The conflict can be solved as it is done in linux-next.
Please pull or let me know if there are problems.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The upcomming IPsec ESP gro callbacks will consume the skb, so prepare for that. Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Add a skb_gro_flush_final helper to prepare for consuming skbs in call_gro_receive. We will extend this helper to not touch the skb if the skb is consumed by a gro callback with a followup patch. We need this to handle the upcomming IPsec ESP callbacks as they reinject the skb to the napi_gro_receive asynchronous. The handler is used in all gro_receive functions that can call the ESP gro handlers. Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
garp_port is only used in net/802/garp.c which is only compiled with CONFIG_GARP enabled. Same goes for mrp_port which is only used in net/802/mrp.c with CONFIG_MRP enabled. Only include the two members in struct net_device if their respective CONFIG_* is enabled. This saves a few bytes in struct net_device in case CONFIG_GARP or CONFIG_MRP are not enabled. Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
The stack must not pass packets to device drivers that are shorter
than the minimum link layer header length.
Previously, packet sockets would drop packets smaller than or equal
to dev->hard_header_len, but this has false positives. Zero length
payload is used over Ethernet. Other link layer protocols support
variable length headers. Support for validation of these protocols
removed the min length check for all protocols.
Introduce an explicit dev->min_header_len parameter and drop all
packets below this value. Initially, set it to non-zero only for
Ethernet and loopback. Other protocols can follow in a patch to
net-next.
Fixes: 9ed988cd5915 ("packet: validate variable length ll headers")
Reported-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In commit 18bfb924f000 ("net: introduce default neigh_construct/destroy
ndo calls for L2 upper devices") we added these ndos to stacked devices
such as team and bond, so that calls will be propagated to mlxsw.
However, previous commit removed the reliance on these ndos and no new
users of these ndos have appeared since above mentioned commit. We can
therefore safely remove this dead code.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All __napi_complete() callers have been converted to use the more standard napi_complete_done(), we can now remove this NAPI method for good. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
We added generic support for busy polling in NAPI layer in linux-4.5 No network driver uses ndo_busy_poll() anymore, we can get rid of the pointer in struct net_device_ops, and its use in sk_busy_loop() Saves NETIF_F_BUSY_POLL features bit. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>