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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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22018a5a54
This adds a simple seq file abstraction that lets you print to a seq
file using ordinary Rust printing syntax.
An example user from Rust Binder:
pub(crate) fn full_debug_print(
&self,
m: &SeqFile,
owner_inner: &mut ProcessInner,
) -> Result<()> {
let prio = self.node_prio();
let inner = self.inner.access_mut(owner_inner);
seq_print!(
m,
" node {}: u{:016x} c{:016x} pri {}:{} hs {} hw {} cs {} cw {}",
self.debug_id,
self.ptr,
self.cookie,
prio.sched_policy,
prio.prio,
inner.strong.has_count,
inner.weak.has_count,
inner.strong.count,
inner.weak.count,
);
if !inner.refs.is_empty() {
seq_print!(m, " proc");
for node_ref in &inner.refs {
seq_print!(m, " {}", node_ref.process.task.pid());
}
}
seq_print!(m, "\n");
for t in &inner.oneway_todo {
t.debug_print_inner(m, " pending async transaction ");
}
Ok(())
}
The `SeqFile` type is marked not thread safe so that `call_printf` can
be a `&self` method. The alternative is to use `self: Pin<&mut Self>`
which is inconvenient, or to have `SeqFile` wrap a pointer instead of
wrapping the C struct directly.
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241001-seqfile-v1-1-dfcd0fc21e96@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
53 lines
1.7 KiB
Rust
53 lines
1.7 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! Seq file bindings.
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//!
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//! C header: [`include/linux/seq_file.h`](srctree/include/linux/seq_file.h)
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use crate::{bindings, c_str, types::NotThreadSafe, types::Opaque};
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/// A utility for generating the contents of a seq file.
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#[repr(transparent)]
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pub struct SeqFile {
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inner: Opaque<bindings::seq_file>,
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_not_send: NotThreadSafe,
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}
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impl SeqFile {
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/// Creates a new [`SeqFile`] from a raw pointer.
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///
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/// # Safety
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///
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/// The caller must ensure that for the duration of 'a the following is satisfied:
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/// * The pointer points at a valid `struct seq_file`.
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/// * The `struct seq_file` is not accessed from any other thread.
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pub unsafe fn from_raw<'a>(ptr: *mut bindings::seq_file) -> &'a SeqFile {
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// SAFETY: The caller ensures that the reference is valid for 'a. There's no way to trigger
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// a data race by using the `&SeqFile` since this is the only thread accessing the seq_file.
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//
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// CAST: The layout of `struct seq_file` and `SeqFile` is compatible.
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unsafe { &*ptr.cast() }
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}
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/// Used by the [`seq_print`] macro.
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pub fn call_printf(&self, args: core::fmt::Arguments<'_>) {
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// SAFETY: Passing a void pointer to `Arguments` is valid for `%pA`.
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unsafe {
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bindings::seq_printf(
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self.inner.get(),
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c_str!("%pA").as_char_ptr(),
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&args as *const _ as *const core::ffi::c_void,
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);
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}
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}
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}
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/// Write to a [`SeqFile`] with the ordinary Rust formatting syntax.
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#[macro_export]
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macro_rules! seq_print {
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($m:expr, $($arg:tt)+) => (
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$m.call_printf(format_args!($($arg)+))
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);
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}
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pub use seq_print;
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