<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/net/core/dst.c, branch v6.2</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'net-next-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next</title>
<updated>2022-12-13T23:47:48+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-12-13T23:47:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7e68dd7d07a28faa2e6574dd6b9dbd90cdeaae91'/>
<id>7e68dd7d07a28faa2e6574dd6b9dbd90cdeaae91</id>
<content type='text'>
Pull networking updates from Paolo Abeni:
 "Core:

   - Allow live renaming when an interface is up

   - Add retpoline wrappers for tc, improving considerably the
     performances of complex queue discipline configurations

   - Add inet drop monitor support

   - A few GRO performance improvements

   - Add infrastructure for atomic dev stats, addressing long standing
     data races

   - De-duplicate common code between OVS and conntrack offloading
     infrastructure

   - A bunch of UBSAN_BOUNDS/FORTIFY_SOURCE improvements

   - Netfilter: introduce packet parser for tunneled packets

   - Replace IPVS timer-based estimators with kthreads to scale up the
     workload with the number of available CPUs

   - Add the helper support for connection-tracking OVS offload

  BPF:

   - Support for user defined BPF objects: the use case is to allocate
     own objects, build own object hierarchies and use the building
     blocks to build own data structures flexibly, for example, linked
     lists in BPF

   - Make cgroup local storage available to non-cgroup attached BPF
     programs

   - Avoid unnecessary deadlock detection and failures wrt BPF task
     storage helpers

   - A relevant bunch of BPF verifier fixes and improvements

   - Veristat tool improvements to support custom filtering, sorting,
     and replay of results

   - Add LLVM disassembler as default library for dumping JITed code

   - Lots of new BPF documentation for various BPF maps

   - Add bpf_rcu_read_{,un}lock() support for sleepable programs

   - Add RCU grace period chaining to BPF to wait for the completion of
     access from both sleepable and non-sleepable BPF programs

   - Add support storing struct task_struct objects as kptrs in maps

   - Improve helper UAPI by explicitly defining BPF_FUNC_xxx integer
     values

   - Add libbpf *_opts API-variants for bpf_*_get_fd_by_id() functions

  Protocols:

   - TCP: implement Protective Load Balancing across switch links

   - TCP: allow dynamically disabling TCP-MD5 static key, reverting back
     to fast[er]-path

   - UDP: Introduce optional per-netns hash lookup table

   - IPv6: simplify and cleanup sockets disposal

   - Netlink: support different type policies for each generic netlink
     operation

   - MPTCP: add MSG_FASTOPEN and FastOpen listener side support

   - MPTCP: add netlink notification support for listener sockets events

   - SCTP: add VRF support, allowing sctp sockets binding to VRF devices

   - Add bridging MAC Authentication Bypass (MAB) support

   - Extensions for Ethernet VPN bridging implementation to better
     support multicast scenarios

   - More work for Wi-Fi 7 support, comprising conversion of all the
     existing drivers to internal TX queue usage

   - IPSec: introduce a new offload type (packet offload) allowing
     complete header processing and crypto offloading

   - IPSec: extended ack support for more descriptive XFRM error
     reporting

   - RXRPC: increase SACK table size and move processing into a
     per-local endpoint kernel thread, reducing considerably the
     required locking

   - IEEE 802154: synchronous send frame and extended filtering support,
     initial support for scanning available 15.4 networks

   - Tun: bump the link speed from 10Mbps to 10Gbps

   - Tun/VirtioNet: implement UDP segmentation offload support

  Driver API:

   - PHY/SFP: improve power level switching between standard level 1 and
     the higher power levels

   - New API for netdev &lt;-&gt; devlink_port linkage

   - PTP: convert existing drivers to new frequency adjustment
     implementation

   - DSA: add support for rx offloading

   - Autoload DSA tagging driver when dynamically changing protocol

   - Add new PCP and APPTRUST attributes to Data Center Bridging

   - Add configuration support for 800Gbps link speed

   - Add devlink port function attribute to enable/disable RoCE and
     migratable

   - Extend devlink-rate to support strict prioriry and weighted fair
     queuing

   - Add devlink support to directly reading from region memory

   - New device tree helper to fetch MAC address from nvmem

   - New big TCP helper to simplify temporary header stripping

  New hardware / drivers:

   - Ethernet:
      - Marvel Octeon CNF95N and CN10KB Ethernet Switches
      - Marvel Prestera AC5X Ethernet Switch
      - WangXun 10 Gigabit NIC
      - Motorcomm yt8521 Gigabit Ethernet
      - Microchip ksz9563 Gigabit Ethernet Switch
      - Microsoft Azure Network Adapter
      - Linux Automation 10Base-T1L adapter

   - PHY:
      - Aquantia AQR112 and AQR412
      - Motorcomm YT8531S

   - PTP:
      - Orolia ART-CARD

   - WiFi:
      - MediaTek Wi-Fi 7 (802.11be) devices
      - RealTek rtw8821cu, rtw8822bu, rtw8822cu and rtw8723du USB
        devices

   - Bluetooth:
      - Broadcom BCM4377/4378/4387 Bluetooth chipsets
      - Realtek RTL8852BE and RTL8723DS
      - Cypress.CYW4373A0 WiFi + Bluetooth combo device

  Drivers:

   - CAN:
      - gs_usb: bus error reporting support
      - kvaser_usb: listen only and bus error reporting support

   - Ethernet NICs:
      - Intel (100G):
         - extend action skbedit to RX queue mapping
         - implement devlink-rate support
         - support direct read from memory
      - nVidia/Mellanox (mlx5):
         - SW steering improvements, increasing rules update rate
         - Support for enhanced events compression
         - extend H/W offload packet manipulation capabilities
         - implement IPSec packet offload mode
      - nVidia/Mellanox (mlx4):
         - better big TCP support
      - Netronome Ethernet NICs (nfp):
         - IPsec offload support
         - add support for multicast filter
      - Broadcom:
         - RSS and PTP support improvements
      - AMD/SolarFlare:
         - netlink extened ack improvements
         - add basic flower matches to offload, and related stats
      - Virtual NICs:
         - ibmvnic: introduce affinity hint support
      - small / embedded:
         - FreeScale fec: add initial XDP support
         - Marvel mv643xx_eth: support MII/GMII/RGMII modes for Kirkwood
         - TI am65-cpsw: add suspend/resume support
         - Mediatek MT7986: add RX wireless wthernet dispatch support
         - Realtek 8169: enable GRO software interrupt coalescing per
           default

   - Ethernet high-speed switches:
      - Microchip (sparx5):
         - add support for Sparx5 TC/flower H/W offload via VCAP
      - Mellanox mlxsw:
         - add 802.1X and MAC Authentication Bypass offload support
         - add ip6gre support

   - Embedded Ethernet switches:
      - Mediatek (mtk_eth_soc):
         - improve PCS implementation, add DSA untag support
         - enable flow offload support
      - Renesas:
         - add rswitch R-Car Gen4 gPTP support
      - Microchip (lan966x):
         - add full XDP support
         - add TC H/W offload via VCAP
         - enable PTP on bridge interfaces
      - Microchip (ksz8):
         - add MTU support for KSZ8 series

   - Qualcomm 802.11ax WiFi (ath11k):
      - support configuring channel dwell time during scan

   - MediaTek WiFi (mt76):
      - enable Wireless Ethernet Dispatch (WED) offload support
      - add ack signal support
      - enable coredump support
      - remain_on_channel support

   - Intel WiFi (iwlwifi):
      - enable Wi-Fi 7 Extremely High Throughput (EHT) PHY capabilities
      - 320 MHz channels support

   - RealTek WiFi (rtw89):
      - new dynamic header firmware format support
      - wake-over-WLAN support"

* tag 'net-next-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2002 commits)
  ipvs: fix type warning in do_div() on 32 bit
  net: lan966x: Remove a useless test in lan966x_ptp_add_trap()
  net: ipa: add IPA v4.7 support
  dt-bindings: net: qcom,ipa: Add SM6350 compatible
  bnxt: Use generic HBH removal helper in tx path
  IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver
  selftests: forwarding: Add bridge MDB test
  selftests: forwarding: Rename bridge_mdb test
  bridge: mcast: Support replacement of MDB port group entries
  bridge: mcast: Allow user space to specify MDB entry routing protocol
  bridge: mcast: Allow user space to add (*, G) with a source list and filter mode
  bridge: mcast: Add support for (*, G) with a source list and filter mode
  bridge: mcast: Avoid arming group timer when (S, G) corresponds to a source
  bridge: mcast: Add a flag for user installed source entries
  bridge: mcast: Expose __br_multicast_del_group_src()
  bridge: mcast: Expose br_multicast_new_group_src()
  bridge: mcast: Add a centralized error path
  bridge: mcast: Place netlink policy before validation functions
  bridge: mcast: Split (*, G) and (S, G) addition into different functions
  bridge: mcast: Do not derive entry type from its filter mode
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull networking updates from Paolo Abeni:
 "Core:

   - Allow live renaming when an interface is up

   - Add retpoline wrappers for tc, improving considerably the
     performances of complex queue discipline configurations

   - Add inet drop monitor support

   - A few GRO performance improvements

   - Add infrastructure for atomic dev stats, addressing long standing
     data races

   - De-duplicate common code between OVS and conntrack offloading
     infrastructure

   - A bunch of UBSAN_BOUNDS/FORTIFY_SOURCE improvements

   - Netfilter: introduce packet parser for tunneled packets

   - Replace IPVS timer-based estimators with kthreads to scale up the
     workload with the number of available CPUs

   - Add the helper support for connection-tracking OVS offload

  BPF:

   - Support for user defined BPF objects: the use case is to allocate
     own objects, build own object hierarchies and use the building
     blocks to build own data structures flexibly, for example, linked
     lists in BPF

   - Make cgroup local storage available to non-cgroup attached BPF
     programs

   - Avoid unnecessary deadlock detection and failures wrt BPF task
     storage helpers

   - A relevant bunch of BPF verifier fixes and improvements

   - Veristat tool improvements to support custom filtering, sorting,
     and replay of results

   - Add LLVM disassembler as default library for dumping JITed code

   - Lots of new BPF documentation for various BPF maps

   - Add bpf_rcu_read_{,un}lock() support for sleepable programs

   - Add RCU grace period chaining to BPF to wait for the completion of
     access from both sleepable and non-sleepable BPF programs

   - Add support storing struct task_struct objects as kptrs in maps

   - Improve helper UAPI by explicitly defining BPF_FUNC_xxx integer
     values

   - Add libbpf *_opts API-variants for bpf_*_get_fd_by_id() functions

  Protocols:

   - TCP: implement Protective Load Balancing across switch links

   - TCP: allow dynamically disabling TCP-MD5 static key, reverting back
     to fast[er]-path

   - UDP: Introduce optional per-netns hash lookup table

   - IPv6: simplify and cleanup sockets disposal

   - Netlink: support different type policies for each generic netlink
     operation

   - MPTCP: add MSG_FASTOPEN and FastOpen listener side support

   - MPTCP: add netlink notification support for listener sockets events

   - SCTP: add VRF support, allowing sctp sockets binding to VRF devices

   - Add bridging MAC Authentication Bypass (MAB) support

   - Extensions for Ethernet VPN bridging implementation to better
     support multicast scenarios

   - More work for Wi-Fi 7 support, comprising conversion of all the
     existing drivers to internal TX queue usage

   - IPSec: introduce a new offload type (packet offload) allowing
     complete header processing and crypto offloading

   - IPSec: extended ack support for more descriptive XFRM error
     reporting

   - RXRPC: increase SACK table size and move processing into a
     per-local endpoint kernel thread, reducing considerably the
     required locking

   - IEEE 802154: synchronous send frame and extended filtering support,
     initial support for scanning available 15.4 networks

   - Tun: bump the link speed from 10Mbps to 10Gbps

   - Tun/VirtioNet: implement UDP segmentation offload support

  Driver API:

   - PHY/SFP: improve power level switching between standard level 1 and
     the higher power levels

   - New API for netdev &lt;-&gt; devlink_port linkage

   - PTP: convert existing drivers to new frequency adjustment
     implementation

   - DSA: add support for rx offloading

   - Autoload DSA tagging driver when dynamically changing protocol

   - Add new PCP and APPTRUST attributes to Data Center Bridging

   - Add configuration support for 800Gbps link speed

   - Add devlink port function attribute to enable/disable RoCE and
     migratable

   - Extend devlink-rate to support strict prioriry and weighted fair
     queuing

   - Add devlink support to directly reading from region memory

   - New device tree helper to fetch MAC address from nvmem

   - New big TCP helper to simplify temporary header stripping

  New hardware / drivers:

   - Ethernet:
      - Marvel Octeon CNF95N and CN10KB Ethernet Switches
      - Marvel Prestera AC5X Ethernet Switch
      - WangXun 10 Gigabit NIC
      - Motorcomm yt8521 Gigabit Ethernet
      - Microchip ksz9563 Gigabit Ethernet Switch
      - Microsoft Azure Network Adapter
      - Linux Automation 10Base-T1L adapter

   - PHY:
      - Aquantia AQR112 and AQR412
      - Motorcomm YT8531S

   - PTP:
      - Orolia ART-CARD

   - WiFi:
      - MediaTek Wi-Fi 7 (802.11be) devices
      - RealTek rtw8821cu, rtw8822bu, rtw8822cu and rtw8723du USB
        devices

   - Bluetooth:
      - Broadcom BCM4377/4378/4387 Bluetooth chipsets
      - Realtek RTL8852BE and RTL8723DS
      - Cypress.CYW4373A0 WiFi + Bluetooth combo device

  Drivers:

   - CAN:
      - gs_usb: bus error reporting support
      - kvaser_usb: listen only and bus error reporting support

   - Ethernet NICs:
      - Intel (100G):
         - extend action skbedit to RX queue mapping
         - implement devlink-rate support
         - support direct read from memory
      - nVidia/Mellanox (mlx5):
         - SW steering improvements, increasing rules update rate
         - Support for enhanced events compression
         - extend H/W offload packet manipulation capabilities
         - implement IPSec packet offload mode
      - nVidia/Mellanox (mlx4):
         - better big TCP support
      - Netronome Ethernet NICs (nfp):
         - IPsec offload support
         - add support for multicast filter
      - Broadcom:
         - RSS and PTP support improvements
      - AMD/SolarFlare:
         - netlink extened ack improvements
         - add basic flower matches to offload, and related stats
      - Virtual NICs:
         - ibmvnic: introduce affinity hint support
      - small / embedded:
         - FreeScale fec: add initial XDP support
         - Marvel mv643xx_eth: support MII/GMII/RGMII modes for Kirkwood
         - TI am65-cpsw: add suspend/resume support
         - Mediatek MT7986: add RX wireless wthernet dispatch support
         - Realtek 8169: enable GRO software interrupt coalescing per
           default

   - Ethernet high-speed switches:
      - Microchip (sparx5):
         - add support for Sparx5 TC/flower H/W offload via VCAP
      - Mellanox mlxsw:
         - add 802.1X and MAC Authentication Bypass offload support
         - add ip6gre support

   - Embedded Ethernet switches:
      - Mediatek (mtk_eth_soc):
         - improve PCS implementation, add DSA untag support
         - enable flow offload support
      - Renesas:
         - add rswitch R-Car Gen4 gPTP support
      - Microchip (lan966x):
         - add full XDP support
         - add TC H/W offload via VCAP
         - enable PTP on bridge interfaces
      - Microchip (ksz8):
         - add MTU support for KSZ8 series

   - Qualcomm 802.11ax WiFi (ath11k):
      - support configuring channel dwell time during scan

   - MediaTek WiFi (mt76):
      - enable Wireless Ethernet Dispatch (WED) offload support
      - add ack signal support
      - enable coredump support
      - remain_on_channel support

   - Intel WiFi (iwlwifi):
      - enable Wi-Fi 7 Extremely High Throughput (EHT) PHY capabilities
      - 320 MHz channels support

   - RealTek WiFi (rtw89):
      - new dynamic header firmware format support
      - wake-over-WLAN support"

* tag 'net-next-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2002 commits)
  ipvs: fix type warning in do_div() on 32 bit
  net: lan966x: Remove a useless test in lan966x_ptp_add_trap()
  net: ipa: add IPA v4.7 support
  dt-bindings: net: qcom,ipa: Add SM6350 compatible
  bnxt: Use generic HBH removal helper in tx path
  IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver
  selftests: forwarding: Add bridge MDB test
  selftests: forwarding: Rename bridge_mdb test
  bridge: mcast: Support replacement of MDB port group entries
  bridge: mcast: Allow user space to specify MDB entry routing protocol
  bridge: mcast: Allow user space to add (*, G) with a source list and filter mode
  bridge: mcast: Add support for (*, G) with a source list and filter mode
  bridge: mcast: Avoid arming group timer when (S, G) corresponds to a source
  bridge: mcast: Add a flag for user installed source entries
  bridge: mcast: Expose __br_multicast_del_group_src()
  bridge: mcast: Expose br_multicast_new_group_src()
  bridge: mcast: Add a centralized error path
  bridge: mcast: Place netlink policy before validation functions
  bridge: mcast: Split (*, G) and (S, G) addition into different functions
  bridge: mcast: Do not derive entry type from its filter mode
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>xfrm: interface: Add unstable helpers for setting/getting XFRM metadata from TC-BPF</title>
<updated>2022-12-06T05:58:27+00:00</updated>
<author>
<name>Eyal Birger</name>
<email>eyal.birger@gmail.com</email>
</author>
<published>2022-12-03T08:46:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=94151f5aa9667c562281abeaaa5e89b9d5c17729'/>
<id>94151f5aa9667c562281abeaaa5e89b9d5c17729</id>
<content type='text'>
This change adds xfrm metadata helpers using the unstable kfunc call
interface for the TC-BPF hooks. This allows steering traffic towards
different IPsec connections based on logic implemented in bpf programs.

This object is built based on the availability of BTF debug info.

When setting the xfrm metadata, percpu metadata dsts are used in order
to avoid allocating a metadata dst per packet.

In order to guarantee safe module unload, the percpu dsts are allocated
on first use and never freed. The percpu pointer is stored in
net/core/filter.c so that it can be reused on module reload.

The metadata percpu dsts take ownership of the original skb dsts so
that they may be used as part of the xfrm transmission logic - e.g.
for MTU calculations.

Signed-off-by: Eyal Birger &lt;eyal.birger@gmail.com&gt;
Link: https://lore.kernel.org/r/20221203084659.1837829-3-eyal.birger@gmail.com
Signed-off-by: Martin KaFai Lau &lt;martin.lau@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This change adds xfrm metadata helpers using the unstable kfunc call
interface for the TC-BPF hooks. This allows steering traffic towards
different IPsec connections based on logic implemented in bpf programs.

This object is built based on the availability of BTF debug info.

When setting the xfrm metadata, percpu metadata dsts are used in order
to avoid allocating a metadata dst per packet.

In order to guarantee safe module unload, the percpu dsts are allocated
on first use and never freed. The percpu pointer is stored in
net/core/filter.c so that it can be reused on module reload.

The metadata percpu dsts take ownership of the original skb dsts so
that they may be used as part of the xfrm transmission logic - e.g.
for MTU calculations.

Signed-off-by: Eyal Birger &lt;eyal.birger@gmail.com&gt;
Link: https://lore.kernel.org/r/20221203084659.1837829-3-eyal.birger@gmail.com
Signed-off-by: Martin KaFai Lau &lt;martin.lau@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: Use call_rcu_hurry() for dst_release()</title>
<updated>2022-11-30T21:17:25+00:00</updated>
<author>
<name>Joel Fernandes (Google)</name>
<email>joel@joelfernandes.org</email>
</author>
<published>2022-11-18T19:19:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=483c26ff63f42e8898ed43aca0b9953bc91f0cd4'/>
<id>483c26ff63f42e8898ed43aca0b9953bc91f0cd4</id>
<content type='text'>
In a networking test on ChromeOS, kernels built with the new
CONFIG_RCU_LAZY=y Kconfig option fail a networking test in the teardown
phase.

This failure may be reproduced as follows: ip netns del &lt;name&gt;

The CONFIG_RCU_LAZY=y Kconfig option was introduced by earlier commits
in this series for the benefit of certain battery-powered systems.
This Kconfig option causes call_rcu() to delay its callbacks in order
to batch them.  This means that a given RCU grace period covers more
callbacks, thus reducing the number of grace periods, in turn reducing
the amount of energy consumed, which increases battery lifetime which
can be a very good thing.  This is not a subtle effect: In some important
use cases, the battery lifetime is increased by more than 10%.

This CONFIG_RCU_LAZY=y option is available only for CPUs that offload
callbacks, for example, CPUs mentioned in the rcu_nocbs kernel boot
parameter passed to kernels built with CONFIG_RCU_NOCB_CPU=y.

Delaying callbacks is normally not a problem because most callbacks do
nothing but free memory.  If the system is short on memory, a shrinker
will kick all currently queued lazy callbacks out of their laziness,
thus freeing their memory in short order.  Similarly, the rcu_barrier()
function, which blocks until all currently queued callbacks are invoked,
will also kick lazy callbacks, thus enabling rcu_barrier() to complete
in a timely manner.

However, there are some cases where laziness is not a good option.
For example, synchronize_rcu() invokes call_rcu(), and blocks until
the newly queued callback is invoked.  It would not be a good for
synchronize_rcu() to block for ten seconds, even on an idle system.
Therefore, synchronize_rcu() invokes call_rcu_hurry() instead of
call_rcu().  The arrival of a non-lazy call_rcu_hurry() callback on a
given CPU kicks any lazy callbacks that might be already queued on that
CPU.  After all, if there is going to be a grace period, all callbacks
might as well get full benefit from it.

Yes, this could be done the other way around by creating a
call_rcu_lazy(), but earlier experience with this approach and
feedback at the 2022 Linux Plumbers Conference shifted the approach
to call_rcu() being lazy with call_rcu_hurry() for the few places
where laziness is inappropriate.

Returning to the test failure, use of ftrace showed that this failure
cause caused by the aadded delays due to this new lazy behavior of
call_rcu() in kernels built with CONFIG_RCU_LAZY=y.

Therefore, make dst_release() use call_rcu_hurry() in order to revert
to the old test-failure-free behavior.

[ paulmck: Apply s/call_rcu_flush/call_rcu_hurry/ feedback from Tejun Heo. ]

Signed-off-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
Cc: David Ahern &lt;dsahern@kernel.org&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: Hideaki YOSHIFUJI &lt;yoshfuji@linux-ipv6.org&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
Cc: Paolo Abeni &lt;pabeni@redhat.com&gt;
Cc: &lt;netdev@vger.kernel.org&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In a networking test on ChromeOS, kernels built with the new
CONFIG_RCU_LAZY=y Kconfig option fail a networking test in the teardown
phase.

This failure may be reproduced as follows: ip netns del &lt;name&gt;

The CONFIG_RCU_LAZY=y Kconfig option was introduced by earlier commits
in this series for the benefit of certain battery-powered systems.
This Kconfig option causes call_rcu() to delay its callbacks in order
to batch them.  This means that a given RCU grace period covers more
callbacks, thus reducing the number of grace periods, in turn reducing
the amount of energy consumed, which increases battery lifetime which
can be a very good thing.  This is not a subtle effect: In some important
use cases, the battery lifetime is increased by more than 10%.

This CONFIG_RCU_LAZY=y option is available only for CPUs that offload
callbacks, for example, CPUs mentioned in the rcu_nocbs kernel boot
parameter passed to kernels built with CONFIG_RCU_NOCB_CPU=y.

Delaying callbacks is normally not a problem because most callbacks do
nothing but free memory.  If the system is short on memory, a shrinker
will kick all currently queued lazy callbacks out of their laziness,
thus freeing their memory in short order.  Similarly, the rcu_barrier()
function, which blocks until all currently queued callbacks are invoked,
will also kick lazy callbacks, thus enabling rcu_barrier() to complete
in a timely manner.

However, there are some cases where laziness is not a good option.
For example, synchronize_rcu() invokes call_rcu(), and blocks until
the newly queued callback is invoked.  It would not be a good for
synchronize_rcu() to block for ten seconds, even on an idle system.
Therefore, synchronize_rcu() invokes call_rcu_hurry() instead of
call_rcu().  The arrival of a non-lazy call_rcu_hurry() callback on a
given CPU kicks any lazy callbacks that might be already queued on that
CPU.  After all, if there is going to be a grace period, all callbacks
might as well get full benefit from it.

Yes, this could be done the other way around by creating a
call_rcu_lazy(), but earlier experience with this approach and
feedback at the 2022 Linux Plumbers Conference shifted the approach
to call_rcu() being lazy with call_rcu_hurry() for the few places
where laziness is inappropriate.

Returning to the test failure, use of ftrace showed that this failure
cause caused by the aadded delays due to this new lazy behavior of
call_rcu() in kernels built with CONFIG_RCU_LAZY=y.

Therefore, make dst_release() use call_rcu_hurry() in order to revert
to the old test-failure-free behavior.

[ paulmck: Apply s/call_rcu_flush/call_rcu_hurry/ feedback from Tejun Heo. ]

Signed-off-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
Cc: David Ahern &lt;dsahern@kernel.org&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: Hideaki YOSHIFUJI &lt;yoshfuji@linux-ipv6.org&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
Cc: Paolo Abeni &lt;pabeni@redhat.com&gt;
Cc: &lt;netdev@vger.kernel.org&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: rename reference+tracking helpers</title>
<updated>2022-06-10T04:52:55+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2022-06-08T04:39:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d62607c3fe45911b2331fac073355a8c914bbde2'/>
<id>d62607c3fe45911b2331fac073355a8c914bbde2</id>
<content type='text'>
Netdev reference helpers have a dev_ prefix for historic
reasons. Renaming the old helpers would be too much churn
but we can rename the tracking ones which are relatively
recent and should be the default for new code.

Rename:
 dev_hold_track()    -&gt; netdev_hold()
 dev_put_track()     -&gt; netdev_put()
 dev_replace_track() -&gt; netdev_ref_replace()

Link: https://lore.kernel.org/r/20220608043955.919359-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Netdev reference helpers have a dev_ prefix for historic
reasons. Renaming the old helpers would be too much churn
but we can rename the tracking ones which are relatively
recent and should be the default for new code.

Rename:
 dev_hold_track()    -&gt; netdev_hold()
 dev_put_track()     -&gt; netdev_put()
 dev_replace_track() -&gt; netdev_ref_replace()

Link: https://lore.kernel.org/r/20220608043955.919359-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: dst: add net device refcount tracking to dst_entry</title>
<updated>2021-12-07T00:05:10+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2021-12-05T04:22:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9038c320001dd07f60736018edf608ac5baca0ab'/>
<id>9038c320001dd07f60736018edf608ac5baca0ab</id>
<content type='text'>
We want to track all dev_hold()/dev_put() to ease leak hunting.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We want to track all dev_hold()/dev_put() to ease leak hunting.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: Remove redundant if statements</title>
<updated>2021-08-05T12:27:50+00:00</updated>
<author>
<name>Yajun Deng</name>
<email>yajun.deng@linux.dev</email>
</author>
<published>2021-08-05T11:55:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1160dfa178eb848327e9dec39960a735f4dc1685'/>
<id>1160dfa178eb848327e9dec39960a735f4dc1685</id>
<content type='text'>
The 'if (dev)' statement already move into dev_{put , hold}, so remove
redundant if statements.

Signed-off-by: Yajun Deng &lt;yajun.deng@linux.dev&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The 'if (dev)' statement already move into dev_{put , hold}, so remove
redundant if statements.

Signed-off-by: Yajun Deng &lt;yajun.deng@linux.dev&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net, bpf: Fix ip6ip6 crash with collect_md populated skbs</title>
<updated>2021-03-10T20:24:18+00:00</updated>
<author>
<name>Daniel Borkmann</name>
<email>daniel@iogearbox.net</email>
</author>
<published>2021-03-10T00:38:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a188bb5638d41aa99090ebf2f85d3505ab13fba5'/>
<id>a188bb5638d41aa99090ebf2f85d3505ab13fba5</id>
<content type='text'>
I ran into a crash where setting up a ip6ip6 tunnel device which was /not/
set to collect_md mode was receiving collect_md populated skbs for xmit.

The BPF prog was populating the skb via bpf_skb_set_tunnel_key() which is
assigning special metadata dst entry and then redirecting the skb to the
device, taking ip6_tnl_start_xmit() -&gt; ipxip6_tnl_xmit() -&gt; ip6_tnl_xmit()
and in the latter it performs a neigh lookup based on skb_dst(skb) where
we trigger a NULL pointer dereference on dst-&gt;ops-&gt;neigh_lookup() since
the md_dst_ops do not populate neigh_lookup callback with a fake handler.

Transform the md_dst_ops into generic dst_blackhole_ops that can also be
reused elsewhere when needed, and use them for the metadata dst entries as
callback ops.

Also, remove the dst_md_discard{,_out}() ops and rely on dst_discard{,_out}()
from dst_init() which free the skb the same way modulo the splat. Given we
will be able to recover just fine from there, avoid any potential splats
iff this gets ever triggered in future (or worse, panic on warns when set).

Fixes: f38a9eb1f77b ("dst: Metadata destinations")
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
I ran into a crash where setting up a ip6ip6 tunnel device which was /not/
set to collect_md mode was receiving collect_md populated skbs for xmit.

The BPF prog was populating the skb via bpf_skb_set_tunnel_key() which is
assigning special metadata dst entry and then redirecting the skb to the
device, taking ip6_tnl_start_xmit() -&gt; ipxip6_tnl_xmit() -&gt; ip6_tnl_xmit()
and in the latter it performs a neigh lookup based on skb_dst(skb) where
we trigger a NULL pointer dereference on dst-&gt;ops-&gt;neigh_lookup() since
the md_dst_ops do not populate neigh_lookup callback with a fake handler.

Transform the md_dst_ops into generic dst_blackhole_ops that can also be
reused elsewhere when needed, and use them for the metadata dst entries as
callback ops.

Also, remove the dst_md_discard{,_out}() ops and rely on dst_discard{,_out}()
from dst_init() which free the skb the same way modulo the splat. Given we
will be able to recover just fine from there, avoid any potential splats
iff this gets ever triggered in future (or worse, panic on warns when set).

Fixes: f38a9eb1f77b ("dst: Metadata destinations")
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: Consolidate common blackhole dst ops</title>
<updated>2021-03-10T20:24:18+00:00</updated>
<author>
<name>Daniel Borkmann</name>
<email>daniel@iogearbox.net</email>
</author>
<published>2021-03-10T00:38:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c4c877b2732466b4c63217baad05c96f775912c7'/>
<id>c4c877b2732466b4c63217baad05c96f775912c7</id>
<content type='text'>
Move generic blackhole dst ops to the core and use them from both
ipv4_dst_blackhole_ops and ip6_dst_blackhole_ops where possible. No
functional change otherwise. We need these also in other locations
and having to define them over and over again is not great.

Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Move generic blackhole dst ops to the core and use them from both
ipv4_dst_blackhole_ops and ip6_dst_blackhole_ops where possible. No
functional change otherwise. We need these also in other locations
and having to define them over and over again is not great.

Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: Correct the comment of dst_dev_put()</title>
<updated>2020-09-10T20:28:57+00:00</updated>
<author>
<name>Miaohe Lin</name>
<email>linmiaohe@huawei.com</email>
</author>
<published>2020-09-10T08:41:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1be107de2ee4b3f0808e2071529364cf4d9a67b9'/>
<id>1be107de2ee4b3f0808e2071529364cf4d9a67b9</id>
<content type='text'>
Since commit 8d7017fd621d ("blackhole_netdev: use blackhole_netdev to
invalidate dst entries"), we use blackhole_netdev to invalidate dst entries
instead of loopback device anymore.

Signed-off-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Since commit 8d7017fd621d ("blackhole_netdev: use blackhole_netdev to
invalidate dst entries"), we use blackhole_netdev to invalidate dst entries
instead of loopback device anymore.

Signed-off-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net/dst: use a smaller percpu_counter batch for dst entries accounting</title>
<updated>2020-05-09T04:33:33+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2020-05-08T01:58:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cf86a086a18095e33e0637cb78cda1fcf5280852'/>
<id>cf86a086a18095e33e0637cb78cda1fcf5280852</id>
<content type='text'>
percpu_counter_add() uses a default batch size which is quite big
on platforms with 256 cpus. (2*256 -&gt; 512)

This means dst_entries_get_fast() can be off by +/- 2*(nr_cpus^2)
(131072 on servers with 256 cpus)

Reduce the batch size to something more reasonable, and
add logic to ip6_dst_gc() to call dst_entries_get_slow()
before calling the _very_ expensive fib6_run_gc() function.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
percpu_counter_add() uses a default batch size which is quite big
on platforms with 256 cpus. (2*256 -&gt; 512)

This means dst_entries_get_fast() can be off by +/- 2*(nr_cpus^2)
(131072 on servers with 256 cpus)

Reduce the batch size to something more reasonable, and
add logic to ip6_dst_gc() to call dst_entries_get_slow()
before calling the _very_ expensive fib6_run_gc() function.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
