The QUSGMII mode is a derivative of Cisco's USXGMII standard. This
standard is pretty similar to SGMII, but allows for faster speeds, and
has the build-in bits for Quad and Octa variants (like QSGMII).

The main difference with SGMII/QSGMII is that USXGMII/QUSGMII re-uses
the preamble to carry various information, named 'Extensions'.

As of today, the USXGMII standard only mentions the "PCH" extension,
which is used to convey timestamps, allowing in-band signaling of PTP
timestamps without having to modify the frame itself.

This commit adds support for that mode. When no extension is in use, it
behaves exactly like QSGMII, although it's not compatible with QSGMII.
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

On the CPSW and ICSS peripherals, there is a possibility that the MDIO
interface returns corrupt data on MDIO reads or writes incorrect data
on MDIO writes. There is also a possibility for the MDIO interface to
become unavailable until the next peripheral reset.

The workaround is to configure the MDIO in manual mode and disable the
MDIO state machine and emulate the MDIO protocol by reading and writing
appropriate fields in MDIO_MANUAL_IF_REG register of the MDIO controller
to manipulate the MDIO clock and data pins.

More details about the errata i2329 and the workaround is available in:
https://www.ti.com/lit/er/sprz487a/sprz487a.pdf

Add implementation to disable MDIO state machine, configure MDIO in manual
mode and achieve MDIO read and writes via MDIO Bitbanging
Signed-off-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

RTL8211F(D)(I)-VD-CG is the pin-to-pin upgrade chip from
RTL8211F(D)(I)-CG.

Add new PHY ID for this chip.
It does not support RTL8211F_PHYCR2 anymore, so remove the w/r operation
of this register.
Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

TCP_LISTEN sockets is a special case. They preserve skb with a newly
connected sock till accept() makes it fully functional socket.
Receive queue of such socket may grow after connected peer
send messages there. Since these messages may contain scm_fds,
we should expose correct fdinfo::scm_fds for listening socket too.
Signed-off-by: Kirill Tkhai <tkhai@ya.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

Size-check a type used for FW communication is packed as expected.
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Signed-off-by: Maksym Glubokiy <maksym.glubokiy@plvision.eu>
Link: https://lore.kernel.org/r/20220818111419.414877-1-maksym.glubokiy@plvision.euSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The skb pointer will be checked in kfree_skb(), so remove the outside check.
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Taehee Yoo <ap420073@gmail.com>
Link: https://lore.kernel.org/r/20220818093114.2449179-1-yangyingliang@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

There are currently 3 ip tunnels that are capable of carrying
L2 traffic: gretap, vxlan and geneve.
They all are capable to inherit the TOS/TTL for the outer
IP-header from the inner frame.

Add a test that verifies that these fields are correctly inherited.

These tests failed before the following commits:
b09ab9c9 ("ip6_tunnel: allow to inherit from VLAN encapsulated IP")
3f8a8447 ("ip6_gre: use actual protocol to select xmit")
41337f52 ("ip6_gre: set DSCP for non-IP")
7ae29fd1 ("ip_tunnel: allow to inherit from VLAN encapsulated IP")
7074732c ("ip_tunnels: allow VXLAN/GENEVE to inherit TOS/TTL from VLAN")
ca2bb695 ("geneve: do not use RT_TOS for IPv6 flowlabel")
b4ab94d6 ("geneve: fix TOS inheriting for ipv4")
Signed-off-by: Matthias May <matthias.may@westermo.com>
Link: https://lore.kernel.org/r/20220817073649.26117-1-matthias.may@westermo.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Sean Anderson says:

====================
net: dpaa: Cleanups in preparation for phylink conversion

This series contains several cleanup patches for dpaa/fman. While they
are intended to prepare for a phylink conversion, they stand on their
own. This series was originally submitted as part of [1].

[1] https://lore.kernel.org/netdev/20220715215954.1449214-1-sean.anderson@seco.com
====================

Link: https://lore.kernel.org/r/20220818161649.2058728-1-sean.anderson@seco.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

This option is present in params, so use it instead of the fman private
version.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

In preparation for moving each of the initialization functions to their
own file, export some common functions so they can be re-used. This adds
an fman prefix to set_multi to make it a bit less genericly-named.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

memac is the only mac which parses fixed links. Move the
parsing/configuring to its initialization function.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Move the reference to our device to mac_device. This way, macs can use
it in their log messages.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Instead of re-matching the compatible string in order to determine the init
function, just store it in the match data. The separate setup functions
aren't needed anymore. Merge their content into init as well. To ensure
everything compiles correctly, we move them to the bottom of the file.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This moves the reading of the PCS property out of the generic probe and
into the mac-specific initialization function. This reduces the
mac-specific jobs done in the top-level probe function.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

There are two ways that GRS can be set: graceful_stop and dtsec_isr. It
is cleared by graceful_start. If it is already set before calling
graceful_stop, then that means that dtsec_isr set it. In that case, we
will not set GRS nor will we clear it (which seems like a bug?). For GTS
the logic is similar, except that there is no one else messing with this
bit (so we will always set and clear it). Simplify the logic by always
setting/clearing GRS/GTS. This is less racy that the previous behavior,
and ensures that we always end up clearing the bits. This can of course
clear GRS while dtsec_isr is waiting, but because we have already done
our own waiting it should be fine.

This is the last user of enum comm_mode, so remove it.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Tested-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

All macs use the same start/stop functions. The actual mac-specific code
lives in enable/disable. Move these functions to an appropriate struct,
and inline the phy enable/disable calls to the caller of start/stop.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Tested-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mac_priv_s->enable() and ->disable() are always called with
a comm_mode of COMM_MODE_RX_AND_TX. Remove this parameter, and refactor
the macs appropriately.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Tested-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This converts the license text of files in the fman directory to use
SPDX license identifiers instead.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Tested-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This converts the MAC portion of the FMan MAC bindings to yaml.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This reverts commit 5417197d, reversing
changes made to 0630f64d.

Reverting to allow addressing review comments.

Link: https://lore.kernel.org/all/4c5dbea0-52a9-1c3d-7547-00ea54c90550@linux.intel.com/Signed-off-by: Jakub Kicinski <kuba@kernel.org>

No conflicts.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add the capability to map non-linear xdp frames in XDP_TX and
ndo_xdp_xmit callback.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://lore.kernel.org/r/20220817173628.109102-1-anthony.l.nguyen@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Petr Machata says:

====================
selftests: mlxsw: Add ordering tests for unified bridge model

Amit Cohen writes:

Commit 798661c7 ("Merge branch 'mlxsw-unified-bridge-conversion-part-6'")
converted mlxsw driver to use unified bridge model. In the legacy model,
when a RIF was created / destroyed, it was firmware's responsibility to
update it in the relevant FID classification records. In the unified bridge
model, this responsibility moved to software.

This set adds tests to check the order of configuration for the following
classifications:
1. {Port, VID} -> FID
2. VID -> FID
3. VNI -> FID (after decapsulation)

In addition, in the legacy model, software is responsible to update a
table which is used to determine the packet's egress VID. Add a test to
check that the order of configuration does not impact switch behavior.

See more details in the commit messages.

Note that the tests supposed to pass also using the legacy model, they
are added now as with the new model they test the driver and not the
firmware.

Patch set overview:
Patch #1 adds test for {Port, VID} -> FID
Patch #2 adds test for VID -> FID
Patch #3 adds test for VNI -> FID
Patch #4 adds test for egress VID classification
====================

Link: https://lore.kernel.org/r/cover.1660747162.git.petrm@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

After routing, the device always consults a table that determines the
packet's egress VID based on {egress RIF, egress local port}. In the
unified bridge model, it is up to software to maintain this table via
REIV register.

The table needs to be updated in the following flows:
1. When a RIF is set on a FID, for each FID's {Port, VID} mapping, a new
   {RIF, Port}->VID mapping should be created.
2. When a {Port, VID} is mapped to a FID and the FID already has a RIF,
   a new {RIF, Port}->VID mapping should be created.

Add a test to verify that packets get the correct VID after routing,
regardless of the order of the configuration.

 # ./egress_vid_classification.sh
 TEST: Add RIF for existing {port, VID}->FID mapping                 [ OK ]
 TEST: Add {port, VID}->FID mapping for FID with a RIF               [ OK ]
Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Before layer 2 forwarding, the device classifies an incoming packet to a
FID. After classification, the FID is known, but also all the attributes of
the FID, such as the router interface (RIF) via which a packet that needs
to be routed will ingress the router block.

For VXLAN decapsulation, the FID classification is done according to the
VNI. When a RIF is added on top of a FID, the existing VNI->FID mapping
should be updated by the software with the new RIF. In addition, when a new
mapping is added for FID which already has a RIF, the correct RIF should
be used for it.

Add a test to verify that packets can be routed after decapsulation which
is done after VNI->FID classification, regardless of the order of the
configuration.

 # ./ingress_rif_conf_vxlan.sh
 TEST: Add RIF for existing VNI->FID mapping                         [ OK ]
 TEST: Add VNI->FID mapping for FID with a RIF                       [ OK ]
Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Before layer 2 forwarding, the device classifies an incoming packet to a
FID. After classification, the FID is known, but also all the attributes of
the FID, such as the router interface (RIF) via which a packet that needs
to be routed will ingress the router block.

For VLAN-aware bridges (802.1Q), the FID classification is done according
to VID. When a RIF is added on top of a FID, the existing VID->FID mapping
should be updated by the software with the new RIF.

We never map multiple VLANs to the same FID using VID->FID, so we cannot
create VID->FID for FID which already has a RIF using 802.1Q. Anyway,
verify that packets can be routed via port which is added after the FID
already has a RIF.

Add a test to verify that packets can be routed after VID->FID
classification, regardless of the order of the configuration.

 # ./ingress_rif_conf_1q.sh
 TEST: Add RIF for existing VID->FID mapping                         [ OK ]
 TEST: Add port to VID->FID mapping for FID with a RIF               [ OK ]
Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Before layer 2 forwarding, the device classifies an incoming packet to a
FID. After classification, the FID is known, but also all the attributes of
the FID, such as the router interface (RIF) via which a packet that needs
to be routed will ingress the router block.

For VLAN-unaware bridges (802.1D), the FID classification is done according
to {Port, VID}. When a RIF is added on top of a FID, all the existing
{Port, VID}->FID mappings should be updated by the software with the new
RIF. In addition, when a new mapping is added for FID which already has a
RIF, the correct RIF should be used for it.

Add a test to verify that packets can be routed after {Port, VID}->FID
classification, regardless of the order of the configuration.

 # ./ingress_rif_conf_1d.sh
 TEST: Add RIF for existing {port, VID}->FID mapping                 [ OK ]
 TEST: Add {port, VID}->FID mapping for FID with a RIF               [ OK ]
Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Get rid of unnecessary txd_pdma pointer in mtk_xdp_submit_frame for loop
since it is actually used at the end of the routine using latest mtk_tx_dma
consumed pointer as reference.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/2c40b0fbb9163a0d62ff897abae17db84a9f3b99.1660669138.git.lorenzo@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Expose MACSEC_SALT_LEN definition to user space to be
used in various user space applications such as iproute.
Iproute will use this as part of adding macsec extended
packet number support.
Reviewed-by: Raed Salem <raeds@nvidia.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Emeel Hakim <ehakim@nvidia.com>
Link: https://lore.kernel.org/r/20220818153229.4721-1-ehakim@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Pull networking fixes from Jakub Kicinski:
 "Including fixes from netfilter.

  Current release - regressions:

   - tcp: fix cleanup and leaks in tcp_read_skb() (the new way BPF
     socket maps get data out of the TCP stack)

   - tls: rx: react to strparser initialization errors

   - netfilter: nf_tables: fix scheduling-while-atomic splat

   - net: fix suspicious RCU usage in bpf_sk_reuseport_detach()

  Current release - new code bugs:

   - mlxsw: ptp: fix a couple of races, static checker warnings and
     error handling

  Previous releases - regressions:

   - netfilter:
      - nf_tables: fix possible module reference underflow in error path
      - make conntrack helpers deal with BIG TCP (skbs > 64kB)
      - nfnetlink: re-enable conntrack expectation events

   - net: fix potential refcount leak in ndisc_router_discovery()

  Previous releases - always broken:

   - sched: cls_route: disallow handle of 0

   - neigh: fix possible local DoS due to net iface start/stop loop

   - rtnetlink: fix module refcount leak in rtnetlink_rcv_msg

   - sched: fix adding qlen to qcpu->backlog in gnet_stats_add_queue_cpu

   - virtio_net: fix endian-ness for RSS

   - dsa: mv88e6060: prevent crash on an unused port

   - fec: fix timer capture timing in `fec_ptp_enable_pps()`

   - ocelot: stats: fix races, integer wrapping and reading incorrect
     registers (the change of register definitions here accounts for
     bulk of the changed LoC in this PR)"

* tag 'net-6.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (77 commits)
  net: moxa: MAC address reading, generating, validity checking
  tcp: handle pure FIN case correctly
  tcp: refactor tcp_read_skb() a bit
  tcp: fix tcp_cleanup_rbuf() for tcp_read_skb()
  tcp: fix sock skb accounting in tcp_read_skb()
  igb: Add lock to avoid data race
  dt-bindings: Fix incorrect "the the" corrections
  net: genl: fix error path memory leak in policy dumping
  stmmac: intel: Add a missing clk_disable_unprepare() call in intel_eth_pci_remove()
  net: ethernet: mtk_eth_soc: fix possible NULL pointer dereference in mtk_xdp_run
  net/mlx5e: Allocate flow steering storage during uplink initialization
  net: mscc: ocelot: report ndo_get_stats64 from the wraparound-resistant ocelot->stats
  net: mscc: ocelot: keep ocelot_stat_layout by reg address, not offset
  net: mscc: ocelot: make struct ocelot_stat_layout array indexable
  net: mscc: ocelot: fix race between ndo_get_stats64 and ocelot_check_stats_work
  net: mscc: ocelot: turn stats_lock into a spinlock
  net: mscc: ocelot: fix address of SYS_COUNT_TX_AGING counter
  net: mscc: ocelot: fix incorrect ndo_get_stats64 packet counters
  net: dsa: felix: fix ethtool 256-511 and 512-1023 TX packet counters
  net: dsa: don't warn in dsa_port_set_state_now() when driver doesn't support it
  ...

Merge tag 'linux-kselftest-next-6.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull Kselftest fix from Shuah Khan:

 - fix landlock test build regression

* tag 'linux-kselftest-next-6.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  selftests/landlock: fix broken include of linux/landlock.h

Pull rtla tool fixes from Steven Rostedt:
 "Fixes for the Real-Time Linux Analysis tooling:

   - Fix tracer name in comments and prints

   - Fix setting up symlinks

   - Allow extra flags to be set in build

   - Consolidate and show all necessary libraries not found in build
     error"

* tag 'trace-rtla-v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  rtla: Consolidate and show all necessary libraries that failed for building
  tools/rtla: Build with EXTRA_{C,LD}FLAGS
  tools/rtla: Fix command symlinks
  rtla: Fix tracer name

Wei Fang says:

====================
Add DT property to disable hibernation mode

The patches add the ability to disable the hibernation mode of AR803x
PHYs. Hibernation mode defaults to enabled after hardware reset on
these PHYs. If the AR803x PHYs enter hibernation mode, they will not
provide any clock. For some MACs, they might need the clocks which
provided by the PHYs to support their own hardware logic.
So, the patches add the support to disable hibernation mode by adding
a boolean:

        qca,disable-hibernation-mode

If one wished to disable hibernation mode to better match with the
specifical MAC, just add this property in the phy node of DT.
====================

Link: https://lore.kernel.org/r/20220818030054.1010660-1-wei.fang@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

When the cable is unplugged, the Atheros AR803x PHYs will enter
hibernation mode after about 10 seconds if the hibernation mode
is enabled and will not provide any clock to the MAC. But for
some MACs, this feature might cause unexpected issues due to the
logic of MACs.
Taking SYNP MAC (stmmac) as an example, if the cable is unplugged
and the "eth0" interface is down, the AR803x PHY will enter
hibernation mode. Then perform the "ifconfig eth0 up" operation,
the stmmac can't be able to complete the software reset operation
and fail to init it's own DMA. Therefore, the "eth0" interface is
failed to ifconfig up. Why does it cause this issue? The truth is
that the software reset operation of the stmmac is designed to
depend on the RX_CLK of PHY.
So, this patch offers an option for the user to determine whether
to disable the hibernation mode of AR803x PHYs.
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The hibernation mode of Atheros AR803x PHYs defaults to be
enabled after hardware reset. When the cable is unplugged,
the PHY will enter hibernation mode after about 10 seconds
and the PHY clocks will be stopped to save power.
However, some MACs need the phy output clock for proper
functioning of their logic. For instance, stmmac needs the
RX_CLK of PHY for software reset to complete.
Therefore, add a DT property to configure the PHY to disable
this hardware hibernation mode.
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This device does not remember its MAC address, so add a possibility
to get it from the platform. If it fails, generate a random address.
This will provide a MAC address early during boot without user space
being involved.

Also remove extra calls to is_valid_ether_addr().

Made after suggestions by Andrew Lunn:
1) Use eth_hw_addr_random() to assign a random MAC address during probe.
2) Remove is_valid_ether_addr() from moxart_mac_open()
3) Add a call to platform_get_ethdev_address() during probe
4) Remove is_valid_ether_addr() from moxart_set_mac_address(). The core does this

v1 -> v2:
Handle EPROBE_DEFER returned from platform_get_ethdev_address().
Move MAC reading code to the beginning of the probe function.
Signed-off-by: Sergei Antonov <saproj@gmail.com>
Suggested-by: Andrew Lunn <andrew@lunn.ch>
CC: Yang Yingliang <yangyingliang@huawei.com>
CC: Pavel Skripkin <paskripkin@gmail.com>
CC: Guobin Huang <huangguobin4@huawei.com>
CC: Yang Wei <yang.wei9@zte.com.cn>
CC: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20220818092317.529557-1-saproj@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Cong Wang says:

====================
tcp: some bug fixes for tcp_read_skb()

This patchset contains 3 bug fixes and 1 minor refactor patch for
tcp_read_skb(). V1 only had the first patch, as Eric prefers to fix all
of them together, I have to group them together.
====================

Link: https://lore.kernel.org/r/20220817195445.151609-1-xiyou.wangcong@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

When skb->len==0, the recv_actor() returns 0 too, but we also use 0
for error conditions. This patch amends this by propagating the errors
to tcp_read_skb() so that we can distinguish skb->len==0 case from
error cases.

Fixes: 04919bed ("tcp: Introduce tcp_read_skb()")
Reported-by: Eric Dumazet <edumazet@google.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

As tcp_read_skb() only reads one skb at a time, the while loop is
unnecessary, we can turn it into an if. This also simplifies the
code logic.

Cc: Eric Dumazet <edumazet@google.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_cleanup_rbuf() retrieves the skb from sk_receive_queue, it
assumes the skb is not yet dequeued. This is no longer true for
tcp_read_skb() case where we dequeue the skb first.

Fix this by introducing a helper __tcp_cleanup_rbuf() which does
not require any skb and calling it in tcp_read_skb().

Fixes: 04919bed ("tcp: Introduce tcp_read_skb()")
Cc: Eric Dumazet <edumazet@google.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>