<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/kernel/rcu, branch v6.6</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'tty-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty</title>
<updated>2023-09-01T16:38:00+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-09-01T16:38:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8e1e49550dc85694abd04d86a8ee36bc98bd8b9e'/>
<id>8e1e49550dc85694abd04d86a8ee36bc98bd8b9e</id>
<content type='text'>
Pull tty/serial driver updates from Greg KH:
 "Here is the big set of tty and serial driver changes for 6.6-rc1.

  Lots of cleanups in here this cycle, and some driver updates. Short
  summary is:

   - Jiri's continued work to make the tty code and apis be a bit more
     sane with regards to modern kernel coding style and types

   - cpm_uart driver updates

   - n_gsm updates and fixes

   - meson driver updates

   - sc16is7xx driver updates

   - 8250 driver updates for different hardware types

   - qcom-geni driver fixes

   - tegra serial driver change

   - stm32 driver updates

   - synclink_gt driver cleanups

   - tty structure size reduction

  All of these have been in linux-next this week with no reported
  issues. The last bit of cleanups from Jiri and the tty structure size
  reduction came in last week, a bit late but as they were just style
  changes and size reductions, I figured they should get into this merge
  cycle so that others can work on top of them with no merge conflicts"

* tag 'tty-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (199 commits)
  tty: shrink the size of struct tty_struct by 40 bytes
  tty: n_tty: deduplicate copy code in n_tty_receive_buf_real_raw()
  tty: n_tty: extract ECHO_OP processing to a separate function
  tty: n_tty: unify counts to size_t
  tty: n_tty: use u8 for chars and flags
  tty: n_tty: simplify chars_in_buffer()
  tty: n_tty: remove unsigned char casts from character constants
  tty: n_tty: move newline handling to a separate function
  tty: n_tty: move canon handling to a separate function
  tty: n_tty: use MASK() for masking out size bits
  tty: n_tty: make n_tty_data::num_overrun unsigned
  tty: n_tty: use time_is_before_jiffies() in n_tty_receive_overrun()
  tty: n_tty: use 'num' for writes' counts
  tty: n_tty: use output character directly
  tty: n_tty: make flow of n_tty_receive_buf_common() a bool
  Revert "tty: serial: meson: Add a earlycon for the T7 SoC"
  Documentation: devices.txt: Fix minors for ttyCPM*
  Documentation: devices.txt: Remove ttySIOC*
  Documentation: devices.txt: Remove ttyIOC*
  serial: 8250_bcm7271: improve bcm7271 8250 port
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull tty/serial driver updates from Greg KH:
 "Here is the big set of tty and serial driver changes for 6.6-rc1.

  Lots of cleanups in here this cycle, and some driver updates. Short
  summary is:

   - Jiri's continued work to make the tty code and apis be a bit more
     sane with regards to modern kernel coding style and types

   - cpm_uart driver updates

   - n_gsm updates and fixes

   - meson driver updates

   - sc16is7xx driver updates

   - 8250 driver updates for different hardware types

   - qcom-geni driver fixes

   - tegra serial driver change

   - stm32 driver updates

   - synclink_gt driver cleanups

   - tty structure size reduction

  All of these have been in linux-next this week with no reported
  issues. The last bit of cleanups from Jiri and the tty structure size
  reduction came in last week, a bit late but as they were just style
  changes and size reductions, I figured they should get into this merge
  cycle so that others can work on top of them with no merge conflicts"

* tag 'tty-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (199 commits)
  tty: shrink the size of struct tty_struct by 40 bytes
  tty: n_tty: deduplicate copy code in n_tty_receive_buf_real_raw()
  tty: n_tty: extract ECHO_OP processing to a separate function
  tty: n_tty: unify counts to size_t
  tty: n_tty: use u8 for chars and flags
  tty: n_tty: simplify chars_in_buffer()
  tty: n_tty: remove unsigned char casts from character constants
  tty: n_tty: move newline handling to a separate function
  tty: n_tty: move canon handling to a separate function
  tty: n_tty: use MASK() for masking out size bits
  tty: n_tty: make n_tty_data::num_overrun unsigned
  tty: n_tty: use time_is_before_jiffies() in n_tty_receive_overrun()
  tty: n_tty: use 'num' for writes' counts
  tty: n_tty: use output character directly
  tty: n_tty: make flow of n_tty_receive_buf_common() a bool
  Revert "tty: serial: meson: Add a earlycon for the T7 SoC"
  Documentation: devices.txt: Fix minors for ttyCPM*
  Documentation: devices.txt: Remove ttySIOC*
  Documentation: devices.txt: Remove ttyIOC*
  serial: 8250_bcm7271: improve bcm7271 8250 port
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'net-next-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next</title>
<updated>2023-08-29T18:33:01+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-08-29T18:33:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bd6c11bc43c496cddfc6cf603b5d45365606dbd5'/>
<id>bd6c11bc43c496cddfc6cf603b5d45365606dbd5</id>
<content type='text'>
Pull networking updates from Paolo Abeni:
 "Core:

   - Increase size limits for to-be-sent skb frag allocations. This
     allows tun, tap devices and packet sockets to better cope with
     large writes operations

   - Store netdevs in an xarray, to simplify iterating over netdevs

   - Refactor nexthop selection for multipath routes

   - Improve sched class lifetime handling

   - Add backup nexthop ID support for bridge

   - Implement drop reasons support in openvswitch

   - Several data races annotations and fixes

   - Constify the sk parameter of routing functions

   - Prepend kernel version to netconsole message

  Protocols:

   - Implement support for TCP probing the peer being under memory
     pressure

   - Remove hard coded limitation on IPv6 specific info placement inside
     the socket struct

   - Get rid of sysctl_tcp_adv_win_scale and use an auto-estimated per
     socket scaling factor

   - Scaling-up the IPv6 expired route GC via a separated list of
     expiring routes

   - In-kernel support for the TLS alert protocol

   - Better support for UDP reuseport with connected sockets

   - Add NEXT-C-SID support for SRv6 End.X behavior, reducing the SR
     header size

   - Get rid of additional ancillary per MPTCP connection struct socket

   - Implement support for BPF-based MPTCP packet schedulers

   - Format MPTCP subtests selftests results in TAP

   - Several new SMC 2.1 features including unique experimental options,
     max connections per lgr negotiation, max links per lgr negotiation

  BPF:

   - Multi-buffer support in AF_XDP

   - Add multi uprobe BPF links for attaching multiple uprobes and usdt
     probes, which is significantly faster and saves extra fds

   - Implement an fd-based tc BPF attach API (TCX) and BPF link support
     on top of it

   - Add SO_REUSEPORT support for TC bpf_sk_assign

   - Support new instructions from cpu v4 to simplify the generated code
     and feature completeness, for x86, arm64, riscv64

   - Support defragmenting IPv(4|6) packets in BPF

   - Teach verifier actual bounds of bpf_get_smp_processor_id() and fix
     perf+libbpf issue related to custom section handling

   - Introduce bpf map element count and enable it for all program types

   - Add a BPF hook in sys_socket() to change the protocol ID from
     IPPROTO_TCP to IPPROTO_MPTCP to cover migration for legacy

   - Introduce bpf_me_mcache_free_rcu() and fix OOM under stress

   - Add uprobe support for the bpf_get_func_ip helper

   - Check skb ownership against full socket

   - Support for up to 12 arguments in BPF trampoline

   - Extend link_info for kprobe_multi and perf_event links

  Netfilter:

   - Speed-up process exit by aborting ruleset validation if a fatal
     signal is pending

   - Allow NLA_POLICY_MASK to be used with BE16/BE32 types

  Driver API:

   - Page pool optimizations, to improve data locality and cache usage

   - Introduce ndo_hwtstamp_get() and ndo_hwtstamp_set() to avoid the
     need for raw ioctl() handling in drivers

   - Simplify genetlink dump operations (doit/dumpit) providing them the
     common information already populated in struct genl_info

   - Extend and use the yaml devlink specs to [re]generate the split ops

   - Introduce devlink selective dumps, to allow SF filtering SF based
     on handle and other attributes

   - Add yaml netlink spec for netlink-raw families, allow route, link
     and address related queries via the ynl tool

   - Remove phylink legacy mode support

   - Support offload LED blinking to phy

   - Add devlink port function attributes for IPsec

  New hardware / drivers:

   - Ethernet:
      - Broadcom ASP 2.0 (72165) ethernet controller
      - MediaTek MT7988 SoC
      - Texas Instruments AM654 SoC
      - Texas Instruments IEP driver
      - Atheros qca8081 phy
      - Marvell 88Q2110 phy
      - NXP TJA1120 phy

   - WiFi:
      - MediaTek mt7981 support

   - Can:
      - Kvaser SmartFusion2 PCI Express devices
      - Allwinner T113 controllers
      - Texas Instruments tcan4552/4553 chips

   - Bluetooth:
      - Intel Gale Peak
      - Qualcomm WCN3988 and WCN7850
      - NXP AW693 and IW624
      - Mediatek MT2925

  Drivers:

   - Ethernet NICs:
      - nVidia/Mellanox:
         - mlx5:
            - support UDP encapsulation in packet offload mode
            - IPsec packet offload support in eswitch mode
            - improve aRFS observability by adding new set of counters
            - extends MACsec offload support to cover RoCE traffic
            - dynamic completion EQs
         - mlx4:
            - convert to use auxiliary bus instead of custom interface
              logic
      - Intel
         - ice:
            - implement switchdev bridge offload, even for LAG
              interfaces
            - implement SRIOV support for LAG interfaces
         - igc:
            - add support for multiple in-flight TX timestamps
      - Broadcom:
         - bnxt:
            - use the unified RX page pool buffers for XDP and non-XDP
            - use the NAPI skb allocation cache
      - OcteonTX2:
         - support Round Robin scheduling HTB offload
         - TC flower offload support for SPI field
      - Freescale:
         - add XDP_TX feature support
      - AMD:
         - ionic: add support for PCI FLR event
         - sfc:
            - basic conntrack offload
            - introduce eth, ipv4 and ipv6 pedit offloads
      - ST Microelectronics:
         - stmmac: maximze PTP timestamping resolution

   - Virtual NICs:
      - Microsoft vNIC:
         - batch ringing RX queue doorbell on receiving packets
         - add page pool for RX buffers
      - Virtio vNIC:
         - add per queue interrupt coalescing support
      - Google vNIC:
         - add queue-page-list mode support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add port range matching tc-flower offload
         - permit enslavement to netdevices with uppers

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - convert to phylink_pcs
      - Renesas:
         - r8A779fx: add speed change support
         - rzn1: enables vlan support

   - Ethernet PHYs:
      - convert mv88e6xxx to phylink_pcs

   - WiFi:
      - Qualcomm Wi-Fi 7 (ath12k):
         - extremely High Throughput (EHT) PHY support
      - RealTek (rtl8xxxu):
         - enable AP mode for: RTL8192FU, RTL8710BU (RTL8188GU),
           RTL8192EU and RTL8723BU
      - RealTek (rtw89):
         - Introduce Time Averaged SAR (TAS) support

   - Connector:
      - support for event filtering"

* tag 'net-next-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1806 commits)
  net: ethernet: mtk_wed: minor change in wed_{tx,rx}info_show
  net: ethernet: mtk_wed: add some more info in wed_txinfo_show handler
  net: stmmac: clarify difference between "interface" and "phy_interface"
  r8152: add vendor/device ID pair for D-Link DUB-E250
  devlink: move devlink_notify_register/unregister() to dev.c
  devlink: move small_ops definition into netlink.c
  devlink: move tracepoint definitions into core.c
  devlink: push linecard related code into separate file
  devlink: push rate related code into separate file
  devlink: push trap related code into separate file
  devlink: use tracepoint_enabled() helper
  devlink: push region related code into separate file
  devlink: push param related code into separate file
  devlink: push resource related code into separate file
  devlink: push dpipe related code into separate file
  devlink: move and rename devlink_dpipe_send_and_alloc_skb() helper
  devlink: push shared buffer related code into separate file
  devlink: push port related code into separate file
  devlink: push object register/unregister notifications into separate helpers
  inet: fix IP_TRANSPARENT error handling
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull networking updates from Paolo Abeni:
 "Core:

   - Increase size limits for to-be-sent skb frag allocations. This
     allows tun, tap devices and packet sockets to better cope with
     large writes operations

   - Store netdevs in an xarray, to simplify iterating over netdevs

   - Refactor nexthop selection for multipath routes

   - Improve sched class lifetime handling

   - Add backup nexthop ID support for bridge

   - Implement drop reasons support in openvswitch

   - Several data races annotations and fixes

   - Constify the sk parameter of routing functions

   - Prepend kernel version to netconsole message

  Protocols:

   - Implement support for TCP probing the peer being under memory
     pressure

   - Remove hard coded limitation on IPv6 specific info placement inside
     the socket struct

   - Get rid of sysctl_tcp_adv_win_scale and use an auto-estimated per
     socket scaling factor

   - Scaling-up the IPv6 expired route GC via a separated list of
     expiring routes

   - In-kernel support for the TLS alert protocol

   - Better support for UDP reuseport with connected sockets

   - Add NEXT-C-SID support for SRv6 End.X behavior, reducing the SR
     header size

   - Get rid of additional ancillary per MPTCP connection struct socket

   - Implement support for BPF-based MPTCP packet schedulers

   - Format MPTCP subtests selftests results in TAP

   - Several new SMC 2.1 features including unique experimental options,
     max connections per lgr negotiation, max links per lgr negotiation

  BPF:

   - Multi-buffer support in AF_XDP

   - Add multi uprobe BPF links for attaching multiple uprobes and usdt
     probes, which is significantly faster and saves extra fds

   - Implement an fd-based tc BPF attach API (TCX) and BPF link support
     on top of it

   - Add SO_REUSEPORT support for TC bpf_sk_assign

   - Support new instructions from cpu v4 to simplify the generated code
     and feature completeness, for x86, arm64, riscv64

   - Support defragmenting IPv(4|6) packets in BPF

   - Teach verifier actual bounds of bpf_get_smp_processor_id() and fix
     perf+libbpf issue related to custom section handling

   - Introduce bpf map element count and enable it for all program types

   - Add a BPF hook in sys_socket() to change the protocol ID from
     IPPROTO_TCP to IPPROTO_MPTCP to cover migration for legacy

   - Introduce bpf_me_mcache_free_rcu() and fix OOM under stress

   - Add uprobe support for the bpf_get_func_ip helper

   - Check skb ownership against full socket

   - Support for up to 12 arguments in BPF trampoline

   - Extend link_info for kprobe_multi and perf_event links

  Netfilter:

   - Speed-up process exit by aborting ruleset validation if a fatal
     signal is pending

   - Allow NLA_POLICY_MASK to be used with BE16/BE32 types

  Driver API:

   - Page pool optimizations, to improve data locality and cache usage

   - Introduce ndo_hwtstamp_get() and ndo_hwtstamp_set() to avoid the
     need for raw ioctl() handling in drivers

   - Simplify genetlink dump operations (doit/dumpit) providing them the
     common information already populated in struct genl_info

   - Extend and use the yaml devlink specs to [re]generate the split ops

   - Introduce devlink selective dumps, to allow SF filtering SF based
     on handle and other attributes

   - Add yaml netlink spec for netlink-raw families, allow route, link
     and address related queries via the ynl tool

   - Remove phylink legacy mode support

   - Support offload LED blinking to phy

   - Add devlink port function attributes for IPsec

  New hardware / drivers:

   - Ethernet:
      - Broadcom ASP 2.0 (72165) ethernet controller
      - MediaTek MT7988 SoC
      - Texas Instruments AM654 SoC
      - Texas Instruments IEP driver
      - Atheros qca8081 phy
      - Marvell 88Q2110 phy
      - NXP TJA1120 phy

   - WiFi:
      - MediaTek mt7981 support

   - Can:
      - Kvaser SmartFusion2 PCI Express devices
      - Allwinner T113 controllers
      - Texas Instruments tcan4552/4553 chips

   - Bluetooth:
      - Intel Gale Peak
      - Qualcomm WCN3988 and WCN7850
      - NXP AW693 and IW624
      - Mediatek MT2925

  Drivers:

   - Ethernet NICs:
      - nVidia/Mellanox:
         - mlx5:
            - support UDP encapsulation in packet offload mode
            - IPsec packet offload support in eswitch mode
            - improve aRFS observability by adding new set of counters
            - extends MACsec offload support to cover RoCE traffic
            - dynamic completion EQs
         - mlx4:
            - convert to use auxiliary bus instead of custom interface
              logic
      - Intel
         - ice:
            - implement switchdev bridge offload, even for LAG
              interfaces
            - implement SRIOV support for LAG interfaces
         - igc:
            - add support for multiple in-flight TX timestamps
      - Broadcom:
         - bnxt:
            - use the unified RX page pool buffers for XDP and non-XDP
            - use the NAPI skb allocation cache
      - OcteonTX2:
         - support Round Robin scheduling HTB offload
         - TC flower offload support for SPI field
      - Freescale:
         - add XDP_TX feature support
      - AMD:
         - ionic: add support for PCI FLR event
         - sfc:
            - basic conntrack offload
            - introduce eth, ipv4 and ipv6 pedit offloads
      - ST Microelectronics:
         - stmmac: maximze PTP timestamping resolution

   - Virtual NICs:
      - Microsoft vNIC:
         - batch ringing RX queue doorbell on receiving packets
         - add page pool for RX buffers
      - Virtio vNIC:
         - add per queue interrupt coalescing support
      - Google vNIC:
         - add queue-page-list mode support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add port range matching tc-flower offload
         - permit enslavement to netdevices with uppers

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - convert to phylink_pcs
      - Renesas:
         - r8A779fx: add speed change support
         - rzn1: enables vlan support

   - Ethernet PHYs:
      - convert mv88e6xxx to phylink_pcs

   - WiFi:
      - Qualcomm Wi-Fi 7 (ath12k):
         - extremely High Throughput (EHT) PHY support
      - RealTek (rtl8xxxu):
         - enable AP mode for: RTL8192FU, RTL8710BU (RTL8188GU),
           RTL8192EU and RTL8723BU
      - RealTek (rtw89):
         - Introduce Time Averaged SAR (TAS) support

   - Connector:
      - support for event filtering"

* tag 'net-next-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1806 commits)
  net: ethernet: mtk_wed: minor change in wed_{tx,rx}info_show
  net: ethernet: mtk_wed: add some more info in wed_txinfo_show handler
  net: stmmac: clarify difference between "interface" and "phy_interface"
  r8152: add vendor/device ID pair for D-Link DUB-E250
  devlink: move devlink_notify_register/unregister() to dev.c
  devlink: move small_ops definition into netlink.c
  devlink: move tracepoint definitions into core.c
  devlink: push linecard related code into separate file
  devlink: push rate related code into separate file
  devlink: push trap related code into separate file
  devlink: use tracepoint_enabled() helper
  devlink: push region related code into separate file
  devlink: push param related code into separate file
  devlink: push resource related code into separate file
  devlink: push dpipe related code into separate file
  devlink: move and rename devlink_dpipe_send_and_alloc_skb() helper
  devlink: push shared buffer related code into separate file
  devlink: push port related code into separate file
  devlink: push object register/unregister notifications into separate helpers
  inet: fix IP_TRANSPARENT error handling
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branches 'doc.2023.07.14b', 'fixes.2023.08.16a', 'rcu-tasks.2023.07.24a', 'rcuscale.2023.07.14b', 'refscale.2023.07.14b', 'torture.2023.08.14a' and 'torturescripts.2023.07.20a' into HEAD</title>
<updated>2023-08-16T21:31:08+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2023-08-16T21:31:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=fe24a0b63278808013e1756e235e0e17e8bae281'/>
<id>fe24a0b63278808013e1756e235e0e17e8bae281</id>
<content type='text'>
doc.2023.07.14b:  Documentation updates.
fixes.2023.08.16a:  Miscellaneous fixes.
rcu-tasks.2023.07.24a:  RCU Tasks updates.
rcuscale.2023.07.14b:  RCU (updater) scalability test updates.
refscale.2023.07.14b:  Reference (reader) scalability test updates.
torture.2023.08.14a:  Other torture-test updates.
torturescripts.2023.07.20a:  Other torture-test scripting updates.
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
doc.2023.07.14b:  Documentation updates.
fixes.2023.08.16a:  Miscellaneous fixes.
rcu-tasks.2023.07.24a:  RCU Tasks updates.
rcuscale.2023.07.14b:  RCU (updater) scalability test updates.
refscale.2023.07.14b:  Reference (reader) scalability test updates.
torture.2023.08.14a:  Other torture-test updates.
torturescripts.2023.07.20a:  Other torture-test scripting updates.
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu: Make the rcu_nocb_poll boot parameter usable via boot config</title>
<updated>2023-08-16T21:27:41+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2023-07-05T23:20:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3292ba0229dbe5f3e79b78b230354ada2888dc29'/>
<id>3292ba0229dbe5f3e79b78b230354ada2888dc29</id>
<content type='text'>
The rcu_nocb_poll kernel boot parameter is defined via early_param(),
whose parsing functions are invoked from parse_early_param() which
is in turn invoked by setup_arch(), which is very early indeed.  It
is invoked so early that the console output timestamps read 0.000000,
in other words, before time begins.

This use of early_param() means that the rcu_nocb_poll kernel boot
parameter cannot usefully be embedded into the kernel image.  Yes, you
can embed it, but setup_boot_config() is invoked from start_kernel()
too late for it to be parsed.

But it makes no sense to parse this parameter so early.  After all,
it cannot do anything until the rcuog kthreads are created, which is
long after rcu_init() time, let alone setup_boot_config() time.

This commit therefore switches the rcu_nocb_poll kernel boot parameter
from early_param() to __setup(), which allows boot-config parsing of
this parameter, in turn allowing it to be embedded into the kernel image.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Reviewed-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The rcu_nocb_poll kernel boot parameter is defined via early_param(),
whose parsing functions are invoked from parse_early_param() which
is in turn invoked by setup_arch(), which is very early indeed.  It
is invoked so early that the console output timestamps read 0.000000,
in other words, before time begins.

This use of early_param() means that the rcu_nocb_poll kernel boot
parameter cannot usefully be embedded into the kernel image.  Yes, you
can embed it, but setup_boot_config() is invoked from start_kernel()
too late for it to be parsed.

But it makes no sense to parse this parameter so early.  After all,
it cannot do anything until the rcuog kthreads are created, which is
long after rcu_init() time, let alone setup_boot_config() time.

This commit therefore switches the rcu_nocb_poll kernel boot parameter
from early_param() to __setup(), which allows boot-config parsing of
this parameter, in turn allowing it to be embedded into the kernel image.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Reviewed-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu: Mark __rcu_irq_enter_check_tick() -&gt;rcu_urgent_qs load</title>
<updated>2023-08-16T21:27:41+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2023-06-27T01:37:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=343640cb5b4ed349b3656ee4b100b36e2ae7e2da'/>
<id>343640cb5b4ed349b3656ee4b100b36e2ae7e2da</id>
<content type='text'>
The rcu_request_urgent_qs_task() function does a cross-CPU store
to -&gt;rcu_urgent_qs, so this commit therefore marks the load in
__rcu_irq_enter_check_tick() with READ_ONCE().

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Reviewed-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The rcu_request_urgent_qs_task() function does a cross-CPU store
to -&gt;rcu_urgent_qs, so this commit therefore marks the load in
__rcu_irq_enter_check_tick() with READ_ONCE().

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Reviewed-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcutorture: Stop right-shifting torture_random() return values</title>
<updated>2023-08-14T22:01:08+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2023-07-12T23:16:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bc19e86e285f679d39e1671e72e2f02ac04de999'/>
<id>bc19e86e285f679d39e1671e72e2f02ac04de999</id>
<content type='text'>
Now that torture_random() uses swahw32(), its callers no longer see
not-so-random low-order bits, as these are now swapped up into the upper
16 bits of the torture_random() function's return value.  This commit
therefore removes the right-shifting of torture_random() return values.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Now that torture_random() uses swahw32(), its callers no longer see
not-so-random low-order bits, as these are now swapped up into the upper
16 bits of the torture_random() function's return value.  This commit
therefore removes the right-shifting of torture_random() return values.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Fix boot-time RCU tasks debug-only deadlock</title>
<updated>2023-08-14T21:58:25+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2023-08-01T19:11:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9d0cce2bc3874dd03f7471ec00ae4acb5a77e43c'/>
<id>9d0cce2bc3874dd03f7471ec00ae4acb5a77e43c</id>
<content type='text'>
In kernels built with CONFIG_PROVE_RCU=y (for example, lockdep kernels),
the following sequence of events can occur:

o	rcu_init_tasks_generic() is invoked just before init is spawned.
	It invokes rcu_spawn_tasks_kthread() and friends.

o	rcu_spawn_tasks_kthread() invokes rcu_spawn_tasks_kthread_generic(),
	which uses kthread_run() to create the needed kthread.

o	Control returns to rcu_init_tasks_generic(), which, because this
	is a CONFIG_PROVE_RCU=y kernel, invokes the version of the
	rcu_tasks_initiate_self_tests() function that actually does
	something, including invoking synchronize_rcu_tasks(), which
	in turn invokes synchronize_rcu_tasks_generic().

o	synchronize_rcu_tasks_generic() sees that the -&gt;kthread_ptr is
	still NULL, because the newly spawned kthread has not yet
	started.

o	The new kthread starts, preempting synchronize_rcu_tasks_generic()
	just after its check.  This kthread invokes rcu_tasks_one_gp(),
	which acquires -&gt;tasks_gp_mutex, and, seeing no work, blocks
	in rcuwait_wait_event().  Note that this step requires either
	a preemptible kernel or a fault-injection-style sleep at the
	beginning of mutex_lock().

o	synchronize_rcu_tasks_generic() resumes and invokes rcu_tasks_one_gp().

o	rcu_tasks_one_gp() attempts to acquire -&gt;tasks_gp_mutex, which
	is still held by the newly spawned kthread's rcu_tasks_one_gp()
	function.  Deadlock.

Because the only reason for -&gt;tasks_gp_mutex is to handle pre-kthread
synchronous grace periods, this commit avoids this deadlock by having
rcu_tasks_one_gp() momentarily release -&gt;tasks_gp_mutex while invoking
rcuwait_wait_event().  This allows the call to rcu_tasks_one_gp() from
synchronize_rcu_tasks_generic() proceed.

Note that it is not necessary to release the mutex anywhere else in
rcu_tasks_one_gp() because rcuwait_wait_event() is the only function
that can block indefinitely.

Reported-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Reported-by: Roy Hopkins &lt;rhopkins@suse.de&gt;
Reported-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Tested-by: Roy Hopkins &lt;rhopkins@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In kernels built with CONFIG_PROVE_RCU=y (for example, lockdep kernels),
the following sequence of events can occur:

o	rcu_init_tasks_generic() is invoked just before init is spawned.
	It invokes rcu_spawn_tasks_kthread() and friends.

o	rcu_spawn_tasks_kthread() invokes rcu_spawn_tasks_kthread_generic(),
	which uses kthread_run() to create the needed kthread.

o	Control returns to rcu_init_tasks_generic(), which, because this
	is a CONFIG_PROVE_RCU=y kernel, invokes the version of the
	rcu_tasks_initiate_self_tests() function that actually does
	something, including invoking synchronize_rcu_tasks(), which
	in turn invokes synchronize_rcu_tasks_generic().

o	synchronize_rcu_tasks_generic() sees that the -&gt;kthread_ptr is
	still NULL, because the newly spawned kthread has not yet
	started.

o	The new kthread starts, preempting synchronize_rcu_tasks_generic()
	just after its check.  This kthread invokes rcu_tasks_one_gp(),
	which acquires -&gt;tasks_gp_mutex, and, seeing no work, blocks
	in rcuwait_wait_event().  Note that this step requires either
	a preemptible kernel or a fault-injection-style sleep at the
	beginning of mutex_lock().

o	synchronize_rcu_tasks_generic() resumes and invokes rcu_tasks_one_gp().

o	rcu_tasks_one_gp() attempts to acquire -&gt;tasks_gp_mutex, which
	is still held by the newly spawned kthread's rcu_tasks_one_gp()
	function.  Deadlock.

Because the only reason for -&gt;tasks_gp_mutex is to handle pre-kthread
synchronous grace periods, this commit avoids this deadlock by having
rcu_tasks_one_gp() momentarily release -&gt;tasks_gp_mutex while invoking
rcuwait_wait_event().  This allows the call to rcu_tasks_one_gp() from
synchronize_rcu_tasks_generic() proceed.

Note that it is not necessary to release the mutex anywhere else in
rcu_tasks_one_gp() because rcuwait_wait_event() is the only function
that can block indefinitely.

Reported-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Reported-by: Roy Hopkins &lt;rhopkins@suse.de&gt;
Reported-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Tested-by: Roy Hopkins &lt;rhopkins@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu-tasks: Permit use of debug-objects with RCU Tasks flavors</title>
<updated>2023-07-31T23:06:57+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2023-07-28T20:33:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cb88f7f51bc6f351a529ff61d0a706c6eae1417a'/>
<id>cb88f7f51bc6f351a529ff61d0a706c6eae1417a</id>
<content type='text'>
Currently, cblist_init_generic() holds a raw spinlock when invoking
INIT_WORK().  This fails in kernels built with CONFIG_DEBUG_OBJECTS=y
due to memory allocation being forbidden while holding a raw spinlock.
But the only reason for holding the raw spinlock is to synchronize
with early boot calls to call_rcu_tasks(), call_rcu_tasks_rude, and,
last but not least, call_rcu_tasks_trace().  These calls also invoke
cblist_init_generic() in order to support early boot queueing of
callbacks.

Except that there are no early boot calls to either of these three
functions, and the BPF guys confirm that they have no plans to add any
such calls.

This commit therefore removes the synchronization and adds a
WARN_ON_ONCE() to catch the case of now-prohibited early boot RCU Tasks
callback queueing.

If early boot queueing is needed, an "initialized" flag may be added to
the rcu_tasks structure.  Then queueing a callback before this flag is set
would initialize the callback list (if needed) and queue the callback.
The decision as to where to queue the callback given the possibility of
non-zero boot CPUs is left as an exercise for the reader.

Reported-by: Jakub Kicinski &lt;kuba@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>
Currently, cblist_init_generic() holds a raw spinlock when invoking
INIT_WORK().  This fails in kernels built with CONFIG_DEBUG_OBJECTS=y
due to memory allocation being forbidden while holding a raw spinlock.
But the only reason for holding the raw spinlock is to synchronize
with early boot calls to call_rcu_tasks(), call_rcu_tasks_rude, and,
last but not least, call_rcu_tasks_trace().  These calls also invoke
cblist_init_generic() in order to support early boot queueing of
callbacks.

Except that there are no early boot calls to either of these three
functions, and the BPF guys confirm that they have no plans to add any
such calls.

This commit therefore removes the synchronization and adds a
WARN_ON_ONCE() to catch the case of now-prohibited early boot RCU Tasks
callback queueing.

If early boot queueing is needed, an "initialized" flag may be added to
the rcu_tasks structure.  Then queueing a callback before this flag is set
would initialize the callback list (if needed) and queue the callback.
The decision as to where to queue the callback given the possibility of
non-zero boot CPUs is left as an exercise for the reader.

Reported-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tty: sysrq: switch sysrq handlers from int to u8</title>
<updated>2023-07-25T17:21:03+00:00</updated>
<author>
<name>Jiri Slaby</name>
<email>jirislaby@kernel.org</email>
</author>
<published>2023-07-12T08:18:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bcb48185eddf72d5e2a9f745aaec030778e3ea35'/>
<id>bcb48185eddf72d5e2a9f745aaec030778e3ea35</id>
<content type='text'>
The passed parameter to sysrq handlers is a key (a character). So change
the type from 'int' to 'u8'. Let it specifically be 'u8' for two
reasons:
* unsigned: unsigned values come from the upper layers (devices) and the
  tty layer assumes unsigned on most places, and
* 8-bit: as that what's supposed to be one day in all the layers built
  on the top of tty. (Currently, we use mostly 'unsigned char' and
  somewhere still only 'char'. (But that also translates to the former
  thanks to -funsigned-char.))

Signed-off-by: Jiri Slaby (SUSE) &lt;jirislaby@kernel.org&gt;
Cc: Richard Henderson &lt;richard.henderson@linaro.org&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Huacai Chen &lt;chenhuacai@kernel.org&gt;
Cc: WANG Xuerui &lt;kernel@xen0n.name&gt;
Cc: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Cc: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Maxime Ripard &lt;mripard@kernel.org&gt;
Cc: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Cc: David Airlie &lt;airlied@gmail.com&gt;
Cc: Daniel Vetter &lt;daniel@ffwll.ch&gt;
Cc: Jason Wessel &lt;jason.wessel@windriver.com&gt;
Cc: Daniel Thompson &lt;daniel.thompson@linaro.org&gt;
Cc: Douglas Anderson &lt;dianders@chromium.org&gt;
Cc: "Rafael J. Wysocki" &lt;rafael@kernel.org&gt;
Cc: Len Brown &lt;len.brown@intel.com&gt;
Cc: Pavel Machek &lt;pavel@ucw.cz&gt;
Cc: "Paul E. McKenney" &lt;paulmck@kernel.org&gt;
Cc: Frederic Weisbecker &lt;frederic@kernel.org&gt;
Cc: Neeraj Upadhyay &lt;quic_neeraju@quicinc.com&gt;
Cc: Joel Fernandes &lt;joel@joelfernandes.org&gt;
Cc: Josh Triplett &lt;josh@joshtriplett.org&gt;
Cc: Boqun Feng &lt;boqun.feng@gmail.com&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Lai Jiangshan &lt;jiangshanlai@gmail.com&gt;
Cc: Zqiang &lt;qiang.zhang1211@gmail.com&gt;
Acked-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt; # DRM
Acked-by: WANG Xuerui &lt;git@xen0n.name&gt; # loongarch
Acked-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Acked-by: Daniel Thompson &lt;daniel.thompson@linaro.org&gt;
Link: https://lore.kernel.org/r/20230712081811.29004-3-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The passed parameter to sysrq handlers is a key (a character). So change
the type from 'int' to 'u8'. Let it specifically be 'u8' for two
reasons:
* unsigned: unsigned values come from the upper layers (devices) and the
  tty layer assumes unsigned on most places, and
* 8-bit: as that what's supposed to be one day in all the layers built
  on the top of tty. (Currently, we use mostly 'unsigned char' and
  somewhere still only 'char'. (But that also translates to the former
  thanks to -funsigned-char.))

Signed-off-by: Jiri Slaby (SUSE) &lt;jirislaby@kernel.org&gt;
Cc: Richard Henderson &lt;richard.henderson@linaro.org&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Huacai Chen &lt;chenhuacai@kernel.org&gt;
Cc: WANG Xuerui &lt;kernel@xen0n.name&gt;
Cc: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Cc: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Maxime Ripard &lt;mripard@kernel.org&gt;
Cc: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Cc: David Airlie &lt;airlied@gmail.com&gt;
Cc: Daniel Vetter &lt;daniel@ffwll.ch&gt;
Cc: Jason Wessel &lt;jason.wessel@windriver.com&gt;
Cc: Daniel Thompson &lt;daniel.thompson@linaro.org&gt;
Cc: Douglas Anderson &lt;dianders@chromium.org&gt;
Cc: "Rafael J. Wysocki" &lt;rafael@kernel.org&gt;
Cc: Len Brown &lt;len.brown@intel.com&gt;
Cc: Pavel Machek &lt;pavel@ucw.cz&gt;
Cc: "Paul E. McKenney" &lt;paulmck@kernel.org&gt;
Cc: Frederic Weisbecker &lt;frederic@kernel.org&gt;
Cc: Neeraj Upadhyay &lt;quic_neeraju@quicinc.com&gt;
Cc: Joel Fernandes &lt;joel@joelfernandes.org&gt;
Cc: Josh Triplett &lt;josh@joshtriplett.org&gt;
Cc: Boqun Feng &lt;boqun.feng@gmail.com&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Lai Jiangshan &lt;jiangshanlai@gmail.com&gt;
Cc: Zqiang &lt;qiang.zhang1211@gmail.com&gt;
Acked-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt; # DRM
Acked-by: WANG Xuerui &lt;git@xen0n.name&gt; # loongarch
Acked-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Acked-by: Daniel Thompson &lt;daniel.thompson@linaro.org&gt;
Link: https://lore.kernel.org/r/20230712081811.29004-3-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu: Clarify rcu_is_watching() kernel-doc comment</title>
<updated>2023-07-19T20:21:28+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2023-05-23T09:22:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c924bf5a43e47d5591d527d39b474f8ca9e63c0e'/>
<id>c924bf5a43e47d5591d527d39b474f8ca9e63c0e</id>
<content type='text'>
Make it clear that this function always returns either true or false
without other planned failure modes.

Reported-by: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Reviewed-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Make it clear that this function always returns either true or false
without other planned failure modes.

Reported-by: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Reviewed-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
