linux.git/rust/kernel/time.rs, branch v7.3-rc2

rust: time: add Delta::as_millis_ceil()

2026-08-11T09:34:06+00:00

Add a ceiling variant, mirroring the existing as_micros_ceil() since
the existing as_millis() truncates towards zero.

Reviewed-by: Gary Guo 
Signed-off-by: FUJITA Tomonori 
Reviewed-by: Andreas Hindborg 
Link: https://patch.msgid.link/20260808062839.1159990-4-tomo@flapping.org
Signed-off-by: Miguel Ojeda

rust: time: add jiffies time unit for Delta

2026-08-11T09:34:06+00:00

Add a Jiffy time unit with isize as its representation and provide
Delta::from_jiffies() and as_jiffies() as the unit-specific
constructor and accessor, mirroring from_nanos()/as_nanos() on the
nanosecond Delta.

Represent the jiffies span as isize: Delta is a signed span (nanoseconds
use i64) and, as a timeout, the value only needs to reach
MAX_JIFFY_OFFSET ((LONG_MAX >> 1) - 1). isize is signed and matches the
kernel's c_long, so it meets both.

Reviewed-by: Gary Guo 
Signed-off-by: FUJITA Tomonori 
Reviewed-by: Andreas Hindborg 
Link: https://patch.msgid.link/20260808062839.1159990-3-tomo@flapping.org
[ Added intra-doc links. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: time: make Delta generic over its time unit

2026-08-11T09:34:06+00:00

Delta hardcodes its value as i64 nanoseconds. A later patch adds a
jiffies span, whose natural representation is isize jiffies rather than
i64 nanoseconds, and a separate type per unit would duplicate the
arithmetic and comparison machinery.

Make Delta generic over its time unit so the jiffies span can reuse that
machinery. The nanosecond Delta keeps its current representation and API
via the default unit parameter, so no functional change.

Reviewed-by: Gary Guo 
Signed-off-by: FUJITA Tomonori 
Reviewed-by: Andreas Hindborg 
Link: https://patch.msgid.link/20260808062839.1159990-2-tomo@flapping.org
[ Reworded to remove stray word. Added intra-doc links. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: time: fix as_micros_ceil() rounding near i64::MAX

2026-08-11T09:34:06+00:00

The ceiling adjustment used saturating_add(NSEC_PER_USEC - 1) before
dividing. Once the nanosecond value gets within NSEC_PER_USEC - 1 of
i64::MAX the addition saturates to i64::MAX, which drops the ceiling
bias and can yield a result one microsecond too small.

Fixes: fae0cdc12340 ("rust: time: Introduce Delta type")
Reported-by: Miguel Ojeda 
Closes: https://lore.kernel.org/rust-for-linux/CANiq72mtS0ABA2JnT5tpz6J9c_mnxY+vyPvghV_ukngWvN8F2w@mail.gmail.com/
Signed-off-by: FUJITA Tomonori 
Acked-by: Andreas Hindborg 
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260807130531.1056209-1-tomo@flapping.org
Signed-off-by: Miguel Ojeda

rust: time: fix as_micros_ceil() to round correctly for negative Delta

2026-07-18T17:07:35+00:00

The ceiling-division idiom `(n + d - 1) / d` only produces the
correct result when `n` is non-negative.

For example, if n = -1000 (exactly -1us), the old code computed (-1000
+ 999) / 1000 == 0 instead of -1.

For negative n, truncating division already rounds towards positive
infinity, so no bias is needed in that case.

Fixes: fae0cdc12340 ("rust: time: Introduce Delta type")
Signed-off-by: FUJITA Tomonori 
Acked-by: Andreas Hindborg 
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260713225235.3243480-1-tomo@flapping.org
Signed-off-by: Miguel Ojeda

rust: time: make ClockSource unsafe trait

2026-03-23T07:29:48+00:00

Mark the ClockSource trait as unsafe and document its safety
requirements. Specifically, implementers must guarantee that their
`ktime_get()` implementation returns a value in the inclusive range
[0, KTIME_MAX].

Update all existing implementations to use `unsafe impl` with
corresponding safety comments.

Note that there could be potential users of a customized clock source [1]
so we don't seal the trait.

Link: https://lore.kernel.org/rust-for-linux/Z9xb1r1x5tOzAIZT@boqun-archlinux/ [1]
Suggested-by: Boqun Feng 
Signed-off-by: FUJITA Tomonori 
Reviewed-by: Alice Ryhl 
Link: https://msgid.link/20250630131011.405219-1-fujita.tomonori@gmail.com
[ Change range expressions in docs. - Andreas ]
Signed-off-by: Andreas Hindborg

rust/time: Add Delta::from_nanos()

2026-03-23T07:29:48+00:00

Since rvkms is going to need to create its own Delta instances, and we
already have functions for creating Delta with every other unit of time.

Signed-off-by: Lyude Paul 
Reviewed-by: Alice Ryhl 
Link: https://msgid.link/20251114184207.459335-1-lyude@redhat.com
Signed-off-by: Andreas Hindborg

rust: time: Implement basic arithmetic operations for Delta

2025-09-04T14:56:48+00:00

While rvkms is only going to be using a few of these, since Deltas are
basically the same as i64 it's easy enough to just implement all of the
basic arithmetic operations for Delta types.

Keep in mind there's one quirk here - the kernel has no support for
i64 % i64 on 32 bit platforms, the closest we have is i64 % i32 through
div_s64_rem(). So, instead of implementing ops::Rem or ops::RemAssign we
simply provide Delta::rem_nanos().

Signed-off-by: Lyude Paul 
Reviewed-by: Daniel Almeida 
Reviewed-by: FUJITA Tomonori 
Reviewed-by: Andreas Hindborg 
Link: https://lore.kernel.org/r/20250820203704.731588-3-lyude@redhat.com
Signed-off-by: Andreas Hindborg

rust: time: Implement Add/Sub for Instant

2025-09-04T14:56:48+00:00

In order to copy the behavior rust currently follows for basic arithmetic
operations and panic if the result of an addition or subtraction results in
a value that would violate the invariants of Instant, but only if the
kernel has overflow checking for rust enabled.

Signed-off-by: Lyude Paul 
Reviewed-by: Alice Ryhl 
Reviewed-by: FUJITA Tomonori 
Reviewed-by: Andreas Hindborg 
Reviewed-by: Daniel Almeida 
Link: https://lore.kernel.org/r/20250820203704.731588-2-lyude@redhat.com
Signed-off-by: Andreas Hindborg

rust: hrtimer: Add HrTimer::expires()

2025-09-04T14:54:39+00:00

Add a simple callback for retrieving the current expiry time for an
HrTimer. In rvkms, we use the HrTimer expiry value in order to calculate
the approximate vblank timestamp during each emulated vblank interrupt.

Signed-off-by: Lyude Paul 
Reviewed-by: Andreas Hindborg 
Link: https://lore.kernel.org/r/20250821193259.964504-8-lyude@redhat.com
Signed-off-by: Andreas Hindborg