<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/kernel/rcu/tasks.h, branch v6.2</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.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-stable.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>rcu-tasks: Make grace-period-age message human-readable</title>
<updated>2022-10-21T17:11:00+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2022-09-29T18:58:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=df83fff75870accd16f1dc26a05c31b3bd5e192f'/>
<id>df83fff75870accd16f1dc26a05c31b3bd5e192f</id>
<content type='text'>
This commit adds a few words to the informative message that appears
every ten seconds in RCU Tasks and RCU Tasks Trace grace periods.
This message currently reads as follows:

rcu_tasks_wait_gp: rcu_tasks grace period 1046 is 10088 jiffies old.

After this change, it provides additional context, instead reading
as follows:

rcu_tasks_wait_gp: rcu_tasks grace period number 1046 (since boot) is 10088 jiffies old.

Reported-by: Alexei Starovoitov &lt;ast@kernel.org&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>
This commit adds a few words to the informative message that appears
every ten seconds in RCU Tasks and RCU Tasks Trace grace periods.
This message currently reads as follows:

rcu_tasks_wait_gp: rcu_tasks grace period 1046 is 10088 jiffies old.

After this change, it provides additional context, instead reading
as follows:

rcu_tasks_wait_gp: rcu_tasks grace period number 1046 (since boot) is 10088 jiffies old.

Reported-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Provide rcu_trace_implies_rcu_gp()</title>
<updated>2022-10-18T17:27:02+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2022-10-14T11:39:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e6c86c513f440bec5f1046539c7e3c6c653842da'/>
<id>e6c86c513f440bec5f1046539c7e3c6c653842da</id>
<content type='text'>
As an accident of implementation, an RCU Tasks Trace grace period also
acts as an RCU grace period.  However, this could change at any time.
This commit therefore creates an rcu_trace_implies_rcu_gp() that currently
returns true to codify this accident.  Code relying on this accident
must call this function to verify that this accident is still happening.

Reported-by: Hou Tao &lt;houtao@huaweicloud.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Martin KaFai Lau &lt;martin.lau@linux.dev&gt;
Link: https://lore.kernel.org/r/20221014113946.965131-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
As an accident of implementation, an RCU Tasks Trace grace period also
acts as an RCU grace period.  However, this could change at any time.
This commit therefore creates an rcu_trace_implies_rcu_gp() that currently
returns true to codify this accident.  Code relying on this accident
must call this function to verify that this accident is still happening.

Reported-by: Hou Tao &lt;houtao@huaweicloud.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Martin KaFai Lau &lt;martin.lau@linux.dev&gt;
Link: https://lore.kernel.org/r/20221014113946.965131-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Ensure RCU Tasks Trace loops have quiescent states</title>
<updated>2022-08-31T12:10:55+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2022-07-18T17:57:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d6ad60635cafe900bcd11ad588d8accb36c36b1b'/>
<id>d6ad60635cafe900bcd11ad588d8accb36c36b1b</id>
<content type='text'>
The RCU Tasks Trace grace-period kthread loops across all CPUs, and
there can be quite a few CPUs, with some commercially available systems
sporting well over a thousand of them.  Some of these loops can feature
IPIs, which can take some time.  This commit therefore places a call to
cond_resched_tasks_rcu_qs() in each such loop.

Link: https://docs.google.com/document/d/1V0YnG1HTWMt9WHJjroiJL9lf-hMrud4v8Fn3fhyY0cI/edit?usp=sharing
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The RCU Tasks Trace grace-period kthread loops across all CPUs, and
there can be quite a few CPUs, with some commercially available systems
sporting well over a thousand of them.  Some of these loops can feature
IPIs, which can take some time.  This commit therefore places a call to
cond_resched_tasks_rcu_qs() in each such loop.

Link: https://docs.google.com/document/d/1V0YnG1HTWMt9WHJjroiJL9lf-hMrud4v8Fn3fhyY0cI/edit?usp=sharing
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Convert RCU_LOCKDEP_WARN() to WARN_ONCE()</title>
<updated>2022-08-31T12:10:54+00:00</updated>
<author>
<name>Zqiang</name>
<email>qiang1.zhang@intel.com</email>
</author>
<published>2022-07-12T08:26:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fcd53c8a4dfa38bafb89efdd0b0f718f3a03f884'/>
<id>fcd53c8a4dfa38bafb89efdd0b0f718f3a03f884</id>
<content type='text'>
Kernels built with CONFIG_PROVE_RCU=y and CONFIG_DEBUG_LOCK_ALLOC=y
attempt to emit a warning when the synchronize_rcu_tasks_generic()
function is called during early boot while the rcu_scheduler_active
variable is RCU_SCHEDULER_INACTIVE.  However the warnings is not
actually be printed because the debug_lockdep_rcu_enabled() returns
false, exactly because the rcu_scheduler_active variable is still equal
to RCU_SCHEDULER_INACTIVE.

This commit therefore replaces RCU_LOCKDEP_WARN() with WARN_ONCE()
to force these warnings to actually be printed.

Signed-off-by: Zqiang &lt;qiang1.zhang@intel.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>
Kernels built with CONFIG_PROVE_RCU=y and CONFIG_DEBUG_LOCK_ALLOC=y
attempt to emit a warning when the synchronize_rcu_tasks_generic()
function is called during early boot while the rcu_scheduler_active
variable is RCU_SCHEDULER_INACTIVE.  However the warnings is not
actually be printed because the debug_lockdep_rcu_enabled() returns
false, exactly because the rcu_scheduler_active variable is still equal
to RCU_SCHEDULER_INACTIVE.

This commit therefore replaces RCU_LOCKDEP_WARN() with WARN_ONCE()
to force these warnings to actually be printed.

Signed-off-by: Zqiang &lt;qiang1.zhang@intel.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Use delayed_work to delay rcu_tasks_verify_self_tests()</title>
<updated>2022-06-21T22:49:38+00:00</updated>
<author>
<name>Waiman Long</name>
<email>longman@redhat.com</email>
</author>
<published>2022-06-14T12:06:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e72ee5e1a866b85cb6c3d4c80a1125976020a7e8'/>
<id>e72ee5e1a866b85cb6c3d4c80a1125976020a7e8</id>
<content type='text'>
Commit 2585014188d5 ("rcu-tasks: Be more patient for RCU Tasks
boot-time testing") fixes false positive rcu_tasks verification check
failure by repeating the test once every second until timeout using
schedule_timeout_uninterruptible().

Since rcu_tasks_verify_selft_tests() is called from do_initcalls()
as a late_initcall, this has the undesirable side effect of delaying
other late_initcall's queued after it by a second or more.  Fix this by
instead using delayed_work to repeat the verification check.

Fixes: 2585014188d5 ("rcu-tasks: Be more patient for RCU Tasks boot-time testing")
Signed-off-by: Waiman Long &lt;longman@redhat.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>
Commit 2585014188d5 ("rcu-tasks: Be more patient for RCU Tasks
boot-time testing") fixes false positive rcu_tasks verification check
failure by repeating the test once every second until timeout using
schedule_timeout_uninterruptible().

Since rcu_tasks_verify_selft_tests() is called from do_initcalls()
as a late_initcall, this has the undesirable side effect of delaying
other late_initcall's queued after it by a second or more.  Fix this by
instead using delayed_work to repeat the verification check.

Fixes: 2585014188d5 ("rcu-tasks: Be more patient for RCU Tasks boot-time testing")
Signed-off-by: Waiman Long &lt;longman@redhat.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Be more patient for RCU Tasks boot-time testing</title>
<updated>2022-06-21T22:49:38+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2022-06-07T22:23:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1cf1144e8473e8c3180ac8b91309e29b6acfd95f'/>
<id>1cf1144e8473e8c3180ac8b91309e29b6acfd95f</id>
<content type='text'>
The RCU-Tasks family of grace-period primitives can take some time to
complete, and the amount of time can depend on the exact hardware and
software configuration.  Some configurations boot up fast enough that the
RCU-Tasks verification process gets false-positive failures.  This commit
therefore allows up to 30 seconds for the grace periods to complete, with
this value adjustable downwards using the rcupdate.rcu_task_stall_timeout
kernel boot parameter.

Reported-by: Matthew Wilcox &lt;willy@infradead.org&gt;
Reported-by: Zhouyi Zhou &lt;zhouzhouyi@gmail.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Tested-by: Zhouyi Zhou &lt;zhouzhouyi@gmail.com&gt;
Tested-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The RCU-Tasks family of grace-period primitives can take some time to
complete, and the amount of time can depend on the exact hardware and
software configuration.  Some configurations boot up fast enough that the
RCU-Tasks verification process gets false-positive failures.  This commit
therefore allows up to 30 seconds for the grace periods to complete, with
this value adjustable downwards using the rcupdate.rcu_task_stall_timeout
kernel boot parameter.

Reported-by: Matthew Wilcox &lt;willy@infradead.org&gt;
Reported-by: Zhouyi Zhou &lt;zhouzhouyi@gmail.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Tested-by: Zhouyi Zhou &lt;zhouzhouyi@gmail.com&gt;
Tested-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Update comments</title>
<updated>2022-06-21T22:49:38+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2022-06-07T04:30:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=eea3423b162d5d5cdc08af23e8ee2c2d1134fd07'/>
<id>eea3423b162d5d5cdc08af23e8ee2c2d1134fd07</id>
<content type='text'>
This commit updates comments to reflect the changes in the series
of commits that eliminated the full task-list scan.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Neeraj Upadhyay &lt;quic_neeraju@quicinc.com&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Cc: Martin KaFai Lau &lt;kafai@fb.com&gt;
Cc: KP Singh &lt;kpsingh@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This commit updates comments to reflect the changes in the series
of commits that eliminated the full task-list scan.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Neeraj Upadhyay &lt;quic_neeraju@quicinc.com&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Cc: Martin KaFai Lau &lt;kafai@fb.com&gt;
Cc: KP Singh &lt;kpsingh@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Disable and enable CPU hotplug in same function</title>
<updated>2022-06-21T22:49:38+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2022-06-08T00:25:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=56096ecd5b04148b6d292e3847c23d4a2a454e94'/>
<id>56096ecd5b04148b6d292e3847c23d4a2a454e94</id>
<content type='text'>
The rcu_tasks_trace_pregp_step() function invokes cpus_read_lock() to
disable CPU hotplug, and a later call to the rcu_tasks_trace_postscan()
function invokes cpus_read_unlock() to re-enable it.  This was absolutely
necessary in the past in order to protect the intervening scan of the full
tasks list, but there is no longer such a scan.  This commit therefore
improves readability by moving the cpus_read_unlock() call to the end
of the rcu_tasks_trace_pregp_step() function.  This commit is a pure
code-motion commit without any (intended) change in functionality.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Neeraj Upadhyay &lt;quic_neeraju@quicinc.com&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Cc: Martin KaFai Lau &lt;kafai@fb.com&gt;
Cc: KP Singh &lt;kpsingh@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The rcu_tasks_trace_pregp_step() function invokes cpus_read_lock() to
disable CPU hotplug, and a later call to the rcu_tasks_trace_postscan()
function invokes cpus_read_unlock() to re-enable it.  This was absolutely
necessary in the past in order to protect the intervening scan of the full
tasks list, but there is no longer such a scan.  This commit therefore
improves readability by moving the cpus_read_unlock() call to the end
of the rcu_tasks_trace_pregp_step() function.  This commit is a pure
code-motion commit without any (intended) change in functionality.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Neeraj Upadhyay &lt;quic_neeraju@quicinc.com&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Cc: Martin KaFai Lau &lt;kafai@fb.com&gt;
Cc: KP Singh &lt;kpsingh@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Eliminate RCU Tasks Trace IPIs to online CPUs</title>
<updated>2022-06-21T22:49:38+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2022-06-03T00:30:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e386b6725798eec07facedf4d4bb710c079fd25c'/>
<id>e386b6725798eec07facedf4d4bb710c079fd25c</id>
<content type='text'>
Currently, the RCU Tasks Trace grace-period kthread IPIs each online CPU
using smp_call_function_single() in order to track any tasks currently in
RCU Tasks Trace read-side critical sections during which the corresponding
task has neither blocked nor been preempted.  These IPIs are annoying
and are also not strictly necessary because any task that blocks or is
preempted within its current RCU Tasks Trace read-side critical section
will be tracked on one of the per-CPU rcu_tasks_percpu structure's
-&gt;rtp_blkd_tasks list.  So the only time that this is a problem is if
one of the CPUs runs through a long-duration RCU Tasks Trace read-side
critical section without a context switch.

Note that the task_call_func() function cannot help here because there is
no safe way to identify the target task.  Of course, the task_call_func()
function will be very useful later, when processing the list of tasks,
but it needs to know the task.

This commit therefore creates a cpu_curr_snapshot() function that returns
a pointer the task_struct structure of some task that happened to be
running on the specified CPU more or less during the time that the
cpu_curr_snapshot() function was executing.  If there was no context
switch during this time, this function will return a pointer to the
task_struct structure of the task that was running throughout.  If there
was a context switch, then the outgoing task will be taken care of by
RCU's context-switch hook, and the incoming task was either already taken
care during some previous context switch, or it is not currently within an
RCU Tasks Trace read-side critical section.  And in this latter case, the
grace period already started, so there is no need to wait on this task.

This new cpu_curr_snapshot() function is invoked on each CPU early in
the RCU Tasks Trace grace-period processing, and the resulting tasks
are queued for later quiescent-state inspection.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Neeraj Upadhyay &lt;quic_neeraju@quicinc.com&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Cc: Martin KaFai Lau &lt;kafai@fb.com&gt;
Cc: KP Singh &lt;kpsingh@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently, the RCU Tasks Trace grace-period kthread IPIs each online CPU
using smp_call_function_single() in order to track any tasks currently in
RCU Tasks Trace read-side critical sections during which the corresponding
task has neither blocked nor been preempted.  These IPIs are annoying
and are also not strictly necessary because any task that blocks or is
preempted within its current RCU Tasks Trace read-side critical section
will be tracked on one of the per-CPU rcu_tasks_percpu structure's
-&gt;rtp_blkd_tasks list.  So the only time that this is a problem is if
one of the CPUs runs through a long-duration RCU Tasks Trace read-side
critical section without a context switch.

Note that the task_call_func() function cannot help here because there is
no safe way to identify the target task.  Of course, the task_call_func()
function will be very useful later, when processing the list of tasks,
but it needs to know the task.

This commit therefore creates a cpu_curr_snapshot() function that returns
a pointer the task_struct structure of some task that happened to be
running on the specified CPU more or less during the time that the
cpu_curr_snapshot() function was executing.  If there was no context
switch during this time, this function will return a pointer to the
task_struct structure of the task that was running throughout.  If there
was a context switch, then the outgoing task will be taken care of by
RCU's context-switch hook, and the incoming task was either already taken
care during some previous context switch, or it is not currently within an
RCU Tasks Trace read-side critical section.  And in this latter case, the
grace period already started, so there is no need to wait on this task.

This new cpu_curr_snapshot() function is invoked on each CPU early in
the RCU Tasks Trace grace-period processing, and the resulting tasks
are queued for later quiescent-state inspection.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Neeraj Upadhyay &lt;quic_neeraju@quicinc.com&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Cc: Martin KaFai Lau &lt;kafai@fb.com&gt;
Cc: KP Singh &lt;kpsingh@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
