Introduce a wrapper around `ktime_t` with a few different useful methods. Rust Binder will use these bindings to compute how many milliseconds a transaction has been active for when dumping the current state of the Binder driver. This replicates the logic in C Binder [1]. For a usage example in Rust Binder, see [2]. ktime_get() cannot be safely called in NMI context. This requirement is not checked by these abstractions, but it is intended that klint [3] or a similar tool will be used to check it in the future.
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| @@ -5,6 +5,9 @@ · 4 unmodified lines | ||
| 5 | 5 | //! This module contains the kernel APIs related to time and timers that |
| 6 | 6 | //! have been ported or wrapped for usage by Rust code in the kernel. |
| 7 | 7 | |
| 8 | +/// The number of nanoseconds per millisecond. | |
| 9 | +pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64; | |
| 10 | + | |
| 8 | 11 | /// The time unit of Linux kernel. One jiffy equals (1/HZ) second. |
| 9 | 12 | pub type Jiffies = core::ffi::c_ulong; |
| 10 | 13 | |
| @@ -18,3 +21,60 @@ pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies { · 7 unmodified lines | ||
| 18 | 21 | // matter what the argument is. |
| 19 | 22 | unsafe { bindings::__msecs_to_jiffies(msecs) } |
| 20 | 23 | } |
| 24 | + | |
| 25 | +/// A Rust wrapper around a `ktime_t`. | |
| 26 | +#[repr(transparent)] | |
| 27 | +#[derive(Copy, Clone)] | |
| 28 | +pub struct Ktime { | |
| 29 | + inner: bindings::ktime_t, | |
| 30 | +} | |
| 31 | + | |
| 32 | +impl Ktime { | |
| 33 | + /// Create a `Ktime` from a raw `ktime_t`. | |
| 34 | + #[inline] | |
| 35 | + pub fn from_raw(inner: bindings::ktime_t) -> Self { | |
| 36 | + Self { inner } | |
| 37 | + } | |
| 38 | + | |
| 39 | + /// Get the current time using `CLOCK_MONOTONIC`. | |
| 40 | + #[inline] | |
| 41 | + pub fn ktime_get() -> Self { | |
| 42 | + // SAFETY: It is always safe to call `ktime_get` outside of NMI context. | |
| 43 | + Self::from_raw(unsafe { bindings::ktime_get() }) | |
| 44 | + } | |
| 45 | + | |
| 46 | + /// Divide the number of nanoseconds by a compile-time constant. | |
| 47 | + #[inline] | |
| 48 | + fn divns_constant<const DIV: i64>(self) -> i64 { | |
| 49 | + self.to_ns() / DIV | |
| 50 | + } | |
| 51 | + | |
| 52 | + /// Returns the number of nanoseconds. | |
| 53 | + #[inline] | |
| 54 | + pub fn to_ns(self) -> i64 { | |
| 55 | + self.inner | |
| 56 | + } | |
| 57 | + | |
| 58 | + /// Returns the number of milliseconds. | |
| 59 | + #[inline] | |
| 60 | + pub fn to_ms(self) -> i64 { | |
| 61 | + self.divns_constant::<NSEC_PER_MSEC>() | |
| 62 | + } | |
| 63 | +} | |
| 64 | + | |
| 65 | +/// Returns the number of milliseconds between two ktimes. | |
| 66 | +#[inline] | |
| 67 | +pub fn ktime_ms_delta(later: Ktime, earlier: Ktime) -> i64 { | |
| 68 | + (later - earlier).to_ms() | |
| 69 | +} | |
| 70 | + | |
| 71 | +impl core::ops::Sub for Ktime { | |
| 72 | + type Output = Ktime; | |
| 73 | + | |
| 74 | + #[inline] | |
| 75 | + fn sub(self, other: Ktime) -> Ktime { | |
| 76 | + Self { | |
| 77 | + inner: self.inner - other.inner, | |
| 78 | + } | |
| 79 | + } | |
| 80 | +} | |