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|
// SPDX-License-Identifier: GPL-2.0
//! Rate limiting support.
//!
//! C header: [`include/linux/ratelimit.h`](srctree/include/linux/ratelimit.h)
use crate::{
bindings,
prelude::*,
types::Opaque, //
};
/// Defines a `static` containing a [`Ratelimit`].
#[macro_export]
macro_rules! ratelimit_state_init {
($name:ident, $interval:expr, $burst:expr $(,)?) => {
#[allow(non_upper_case_globals)]
static $name: $crate::ratelimit::Ratelimit = {
let name = $crate::c_str!(::core::stringify!($name));
let interval = $interval;
let burst = $burst;
// SAFETY: This will be stored in static memory.
unsafe { $crate::ratelimit::Ratelimit::new_static(name, interval, burst) }
};
};
}
pub use ratelimit_state_init;
/// Rate limiter state.
///
/// # Invariants
///
/// The `inner` field contains an initialized `struct ratelimit_state`.
#[pin_data(PinnedDrop)]
#[repr(transparent)]
pub struct Ratelimit {
#[pin]
inner: Opaque<bindings::ratelimit_state>,
}
// SAFETY: `Ratelimit` is safe to be sent to any task.
unsafe impl Send for Ratelimit {}
// SAFETY: `Ratelimit` is safe to be accessed concurrently as it is protected by an internal
// spinlock.
unsafe impl Sync for Ratelimit {}
impl Ratelimit {
/// Constructs a [`Ratelimit`] with the specified configuration.
///
/// If `interval` is zero, then no rate limit is applied.
#[inline]
pub fn new(interval: i32, burst: i32) -> impl PinInit<Self> {
// INVARIANT: This creates a `Ratelimit` containing an initialized `struct ratelimit_state`
pin_init!(Self {
inner <- Opaque::ffi_init(|slot: *mut bindings::ratelimit_state| {
// SAFETY: `slot` is a valid pointer to an uninitialized `struct ratelimit_state`.
// The memory is pinned so it remains valid until `ratelimit_state_exit` is called.
unsafe { bindings::ratelimit_state_init(slot, interval, burst) };
}),
})
}
/// Constructs a [`Ratelimit`] with the default configuration.
#[inline]
pub fn new_default() -> impl PinInit<Self> {
Ratelimit::new(Ratelimit::DEFAULT_INTERVAL, Ratelimit::DEFAULT_BURST)
}
/// Constructs a [`Ratelimit`] with the specified configuration.
///
/// The name will be used for the lockdep name of the internal spinlock. See [`Self::new`] for
/// the meaning of `interval` and `burst`.
///
/// # Safety
///
/// The resulting value must be stored in static memory.
#[inline]
pub const unsafe fn new_static(name: &'static CStr, interval: i32, burst: i32) -> Self {
// INVARIANT: This creates a `Ratelimit` containing an initialized `struct ratelimit_state`.
Self {
inner: Opaque::new(bindings::ratelimit_state {
lock: kernel::sync::lock::spinlock::raw_spin_lock_unlocked(name),
interval,
burst,
..pin_init::zeroed()
}),
}
}
/// The default interval used for rate limiting.
pub const DEFAULT_INTERVAL: i32 = bindings::DEFAULT_RATELIMIT_INTERVAL as i32;
/// The default burst size.
pub const DEFAULT_BURST: i32 = bindings::DEFAULT_RATELIMIT_BURST as i32;
/// Check if an action should be rate-limited.
///
/// Returns [`true`] if the action is allowed, and [`false`] if it should be suppressed.
#[inline]
pub fn ratelimit(&self, func: &CStr) -> bool {
// SAFETY: `self.inner.get()` is a valid pointer to a `struct ratelimit_state`.
// The lifetime of `func` ensures the pointer remains valid for the duration of the call.
// The C function `___ratelimit` handles its own internal locking, so it is safe to call
// concurrently.
unsafe { bindings::___ratelimit(self.inner.get(), func.as_char_ptr()) != 0 }
}
}
#[pinned_drop]
impl PinnedDrop for Ratelimit {
#[inline]
fn drop(self: Pin<&mut Self>) {
// SAFETY: By the type invariants, this struct contains an initialized `struct
// ratelimit_state`.
unsafe { bindings::ratelimit_state_exit(self.inner.get()) };
}
}
/// Helper macro to implement ratelimited printing.
#[macro_export]
#[doc(hidden)]
macro_rules! print_ratelimited {
($print_macro:ident, $($arg:tt)*) => {{
$crate::ratelimit::ratelimit_state_init!(
_rs,
$crate::ratelimit::Ratelimit::DEFAULT_INTERVAL,
$crate::ratelimit::Ratelimit::DEFAULT_BURST,
);
let loc = $crate::c_str!(::core::concat!(::core::file!(), ":", ::core::line!()));
if $crate::ratelimit::Ratelimit::ratelimit(&_rs, loc) {
$crate::$print_macro!($($arg)*);
}
}};
}
/// Prints an emergency-level message (level 0) if allowed by a rate limiter.
#[macro_export]
macro_rules! pr_emerg_ratelimited (
($($arg:tt)*) => (
$crate::print_ratelimited!(pr_emerg, $($arg)*)
)
);
/// Prints an alert-level message (level 1) if allowed by a rate limiter.
#[macro_export]
macro_rules! pr_alert_ratelimited (
($($arg:tt)*) => (
$crate::print_ratelimited!(pr_alert, $($arg)*)
)
);
/// Prints a critical-level message (level 2) if allowed by a rate limiter.
#[macro_export]
macro_rules! pr_crit_ratelimited (
($($arg:tt)*) => (
$crate::print_ratelimited!(pr_crit, $($arg)*)
)
);
/// Prints an error-level message (level 3) if allowed by a rate limiter.
#[macro_export]
macro_rules! pr_err_ratelimited (
($($arg:tt)*) => (
$crate::print_ratelimited!(pr_err, $($arg)*)
)
);
/// Prints a warning-level message (level 4) if allowed by a rate limiter.
#[macro_export]
macro_rules! pr_warn_ratelimited (
($($arg:tt)*) => (
$crate::print_ratelimited!(pr_warn, $($arg)*)
)
);
/// Prints a notice-level message (level 5) if allowed by a rate limiter.
#[macro_export]
macro_rules! pr_notice_ratelimited (
($($arg:tt)*) => (
$crate::print_ratelimited!(pr_notice, $($arg)*)
)
);
/// Prints an info-level message (level 6) if allowed by a rate limiter.
#[macro_export]
macro_rules! pr_info_ratelimited (
($($arg:tt)*) => (
$crate::print_ratelimited!(pr_info, $($arg)*)
)
);
/// Prints a debug-level message (level 7) if allowed by a rate limiter.
#[macro_export]
macro_rules! pr_debug_ratelimited (
($($arg:tt)*) => (
if cfg!(debug_assertions) {
$crate::print_ratelimited!(pr_debug, $($arg)*)
}
)
);
|
