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Kernel Source and devicetree for NOTHING Phone(3a) and Phone(3a)Pro
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Joel Fernandes (Google) 72fdf7f606 UPSTREAM: percpu-refcount: Use call_rcu_hurry() for atomic switch 
Earlier commits in this series allow battery-powered systems to build
their kernels with the default-disabled CONFIG_RCU_LAZY=y Kconfig option.
This Kconfig option causes call_rcu() to delay its callbacks in order to
batch callbacks.  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.

And another call_rcu() instance that cannot be lazy is the one on the
percpu refcounter's "per-CPU to atomic switch" code path, which
uses RCU when switching to atomic mode.  The enqueued callback
wakes up waiters waiting in the percpu_ref_switch_waitq.  Allowing
this callback to be lazy would result in unacceptable slowdowns for
users of per-CPU refcounts, such as blk_pre_runtime_suspend().

Therefore, make __percpu_ref_switch_to_atomic() use call_rcu_hurry()
in order to revert to the old behavior.

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

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: <linux-mm@kvack.org>
(cherry picked from commit 343a72e5e37d380b70534fae3acd7e5e39adb769)

Bug: 258241771
Signed-off-by: Joel Fernandes <joelaf@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/4909039
Reviewed-by: Sean Paul <sean@poorly.run>
Reviewed-by: Vineeth Pillai <vineethrp@google.com>
Reviewed-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Qais Yousef <qyousef@google.com>
Change-Id: Icc325f69d0df1a37b6f1de02a284e1fabf20e366
2024-01-19 00:10:44 +00:00
android ANDROID: Update the ABI symbol list 2024-01-18 23:58:21 +00:00
arch ANDROID: gki_defconfig: Set CONFIG_IDLE_INJECT and CONFIG_CPU_IDLE_THERMAL into y 2024-01-10 00:12:51 +00:00
block This is the 6.1.57 stable release 2023-11-02 07:05:54 +00:00
certs This is the 6.1.11 stable release 2023-02-09 13:29:55 +00:00
crypto Merge branch 'android14-6.1' into branch 'android14-6.1-lts' 2023-10-31 17:20:05 +00:00
Documentation FROMGIT: maple_tree: update the documentation of maple tree 2024-01-04 22:44:38 +00:00
drivers UPSTREAM: scsi/scsi_error: Use call_rcu_hurry() instead of call_rcu() 2024-01-19 00:10:44 +00:00
fs FROMGIT: f2fs: do not return EFSCORRUPTED, but try to run online repair 2024-01-04 10:39:11 +00:00
include UPSTREAM: rcu: Update synchronize_rcu_mult() comment for call_rcu_hurry() 2024-01-19 00:10:44 +00:00
init ANDROID: KMI workaround for CONFIG_NETFILTER_FAMILY_BRIDGE 2024-01-09 23:37:43 +00:00
io_uring UPSTREAM: io_uring: use call_rcu_hurry if signaling an eventfd 2024-01-19 00:10:44 +00:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel UPSTREAM: rcu/rcutorture: Use call_rcu_hurry() where needed 2024-01-19 00:10:44 +00:00
lib UPSTREAM: percpu-refcount: Use call_rcu_hurry() for atomic switch 2024-01-19 00:10:44 +00:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm ANDROID: GKI: add vendor hooks for swapping in ahead 2024-01-12 18:47:42 +00:00
net UPSTREAM: netfilter: nf_tables: bail out on mismatching dynset and set expressions 2024-01-17 16:48:40 +00:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples Merge 6.1.55 into android14-6.1-lts 2023-10-26 18:58:32 +00:00
scripts ANDROID: Snapshot Mainline's version of checkpatch.pl 2023-12-15 09:36:46 +00:00
security This is the 6.1.57 stable release 2023-11-02 07:05:54 +00:00
sound UPSTREAM: ASoC: soc-compress: Fix deadlock in soc_compr_open_fe 2023-11-30 18:09:27 +00:00
tools FROMGIT: maple_tree: update check_forking() and bench_forking() 2024-01-04 22:44:38 +00:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore ANDROID: add Android KABI build files to root .gitignore file 2023-06-09 13:12:00 +00:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
BUILD.bazel ANDROID: GKI: Add initial symbol list for honda 2024-01-17 01:26:43 +00:00
build.config.aarch64 ANDROID: Move NDK_TRIPLE to build.config.constants. 2023-02-14 14:13:51 -08:00
build.config.allmodconfig ANDROID: Revert "ANDROID: allmodconfig: disable WERROR" 2023-08-21 17:29:29 +01:00
build.config.allmodconfig.aarch64
build.config.allmodconfig.arm
build.config.allmodconfig.x86_64
build.config.amlogic ANDROID: Unnest MAKE_GOALS from build configs 2023-05-02 13:37:21 +00:00
build.config.arm ANDROID: kleaf: move NDK_TRIPLE for arm to build.config.constants. 2023-05-09 22:36:11 +00:00
build.config.common ANDROID: 6/16/2023 KMI update 2023-06-16 20:49:51 +00:00
build.config.constants ANDROID: clang: update to 17.0.2 2023-05-15 18:53:36 +00:00
build.config.crashdump ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.crashdump.aarch64 ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.crashdump.x86_64 ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.db845c ANDROID: db845c: Remove MAKE_GOALS from build.config 2023-05-15 07:01:39 +00:00
build.config.gki ANDROID: GKI: Source GKI_BUILD_CONFIG_FRAGMENT after setting all variables 2022-12-27 13:52:08 -08:00
build.config.gki-debug.aarch64
build.config.gki-debug.x86_64
build.config.gki.aarch64 ANDROID: Delete MODULES_LIST from build configs. 2023-06-21 11:18:02 +00:00
build.config.gki.aarch64.fips140 ANDROID: fips140: add kernel crypto module 2023-01-09 21:33:43 +00:00
build.config.gki.riscv64 ANDROID: Delete MODULES_LIST from build configs. 2023-06-21 11:18:02 +00:00
build.config.gki.x86_64 ANDROID: Delete MODULES_LIST from build configs. 2023-06-21 11:18:02 +00:00
build.config.gki_kasan ANDROID: build.config: re-disable LTO properly for KASAN 2022-03-24 12:41:35 -07:00
build.config.gki_kasan.aarch64
build.config.gki_kasan.x86_64
build.config.gki_kprobes
build.config.gki_kprobes.aarch64
build.config.gki_kprobes.x86_64
build.config.khwasan
build.config.microdroid ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.microdroid.aarch64 ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.microdroid.x86_64 ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.riscv64 ANDROID: GKI: Add 64-bit RISC-V config 2022-12-08 20:01:15 +00:00
build.config.rockchip ANDROID: GKI: Add rockchip fragment and build.config 2023-09-19 17:36:15 +00:00
build.config.rockpi4 ANDROID: db845c: Remove MAKE_GOALS from build.config 2023-05-15 07:01:39 +00:00
build.config.x86_64 ANDROID: Move NDK_TRIPLE to build.config.constants. 2023-02-14 14:13:51 -08:00
COPYING
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig ANDROID: kbuild: add Kconfig support for external modules 2021-12-13 18:33:18 +00:00
Kconfig.ext ANDROID: kbuild: add Kconfig support for external modules 2021-12-13 18:33:18 +00:00
MAINTAINERS Merge branch 'android14-6.1' into branch 'android14-6.1-lts' 2023-10-31 17:20:05 +00:00
Makefile This is the 6.1.57 stable release 2023-11-02 07:05:54 +00:00
modules.bzl ANDROID: kleaf: Remove ptp_kvm.ko from i386 modules 2023-08-31 17:47:21 +00:00
OWNERS ANDROID: Enable GKI Dr. No Enforcement 2023-06-15 09:54:33 +01:00
OWNERS_DrNo ANDROID: Updating OWNERS_DrNo 2022-08-22 16:34:52 +00:00
README
README.md

README.md

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

    • Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux, additions of EXPORT_SYMBOL_GPL() require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export.
    • When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.

  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass scripts/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry picked from commit ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry picked from commit ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [joe: Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • add a Bug: tag with the Android bug (required for patches not accepted into a maintainer tree)
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)