+ sched-add-need-resched-timed-wait-interface.patch added to mm-new branch

+ sched-add-need-resched-timed-wait-interface.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: sched: add need-resched timed wait interface
has been added to the -mm mm-new branch.  Its filename is
     sched-add-need-resched-timed-wait-interface.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/sched-add-need-resched-timed-wait-interface.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Ankur Arora <ankur.a.arora@oracle.com>
Subject: sched: add need-resched timed wait interface
Date: Wed, 8 Apr 2026 17:55:35 +0530

Add tif_bitset_relaxed_wait() (and tif_need_resched_relaxed_wait() which
wraps it) which takes the thread_info bit and timeout duration as
parameters and waits until the bit is set or for the expiration of the
timeout.

The wait is implemented via smp_cond_load_relaxed_timeout().

smp_cond_load_relaxed_timeout() essentially provides the pattern used in
poll_idle() where we spin in a loop waiting for the flag to change until a
timeout occurs.

tif_need_resched_relaxed_wait() allows us to abstract out the internals
of waiting, scheduler specific details etc.

Placed in linux/sched/idle.h instead of linux/thread_info.h to work
around recursive include hell.

Link: https://lore.kernel.org/20260408122538.3610871-12-ankur.a.arora@oracle.com
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Gow <davidgow@google.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Haris Okanovic <harisokn@amazon.com>
Cc: Konrad Dybcio <konradybcio@kernel.org>
Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/sched/idle.h |   29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

--- a/include/linux/sched/idle.h~sched-add-need-resched-timed-wait-interface
+++ a/include/linux/sched/idle.h
@@ -3,6 +3,7 @@
 #define _LINUX_SCHED_IDLE_H
 
 #include <linux/sched.h>
+#include <linux/sched/clock.h>
 
 enum cpu_idle_type {
 	__CPU_NOT_IDLE = 0,
@@ -113,4 +114,32 @@ static __always_inline void current_clr_
 }
 #endif
 
+/*
+ * Caller needs to make sure that the thread context cannot be preempted
+ * or migrated, so current_thread_info() cannot change from under us.
+ *
+ * This also allows us to safely stay in the local_clock domain.
+ */
+static __always_inline bool tif_bitset_relaxed_wait(int tif, u64 timeout_ns)
+{
+	unsigned long flags;
+
+	flags = smp_cond_load_relaxed_timeout(&current_thread_info()->flags,
+					      (VAL & BIT(tif)),
+					      local_clock_noinstr(),
+					      timeout_ns);
+	return flags & BIT(tif);
+}
+
+/**
+ * tif_need_resched_relaxed_wait() - Wait for need-resched being set
+ * with no ordering guarantees until a timeout expires.
+ *
+ * @timeout_ns: timeout value.
+ */
+static __always_inline bool tif_need_resched_relaxed_wait(u64 timeout_ns)
+{
+	return tif_bitset_relaxed_wait(TIF_NEED_RESCHED, timeout_ns);
+}
+
 #endif /* _LINUX_SCHED_IDLE_H */
_

Patches currently in -mm which might be from ankur.a.arora@oracle.com are

asm-generic-barrier-add-smp_cond_load_relaxed_timeout.patch
arm64-barrier-support-smp_cond_load_relaxed_timeout.patch
arm64-delay-move-some-constants-out-to-a-separate-header.patch
arm64-support-wfet-in-smp_cond_load_relaxed_timeout.patch
arm64-rqspinlock-remove-private-copy-of-smp_cond_load_acquire_timewait.patch
asm-generic-barrier-add-smp_cond_load_acquire_timeout.patch
atomic-add-atomic_cond_read__timeout.patch
locking-atomic-scripts-build-atomic_long_cond_read__timeout.patch
bpf-rqspinlock-switch-check_timeout-to-a-clock-interface.patch
bpf-rqspinlock-use-smp_cond_load_acquire_timeout.patch
sched-add-need-resched-timed-wait-interface.patch
cpuidle-poll_state-wait-for-need-resched-via-tif_need_resched_relaxed_wait.patch
kunit-enable-testing-smp_cond_load_relaxed_timeout.patch
kunit-add-tests-for-smp_cond_load_relaxed_timeout.patch