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authorWedson Almeida Filho <walmeida@microsoft.com>2023-04-11 08:45:39 +0300
committerMiguel Ojeda <ojeda@kernel.org>2023-04-22 01:20:00 +0300
commit313c4281bc9dfa98d76a71b16a684af1c52e7751 (patch)
treefca1f406ce6b7f784bf87f7b14f6c4437f3f3fed /rust
parentf1fbd6a864d417443cdacd6bfdb7fd626993da7e (diff)
downloadlinux-313c4281bc9dfa98d76a71b16a684af1c52e7751.tar.xz
rust: add basic `Task`
It is an abstraction for C's `struct task_struct`. It implements `AlwaysRefCounted`, so the refcount of the wrapped object is managed safely on the Rust side. Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com> Link: https://lore.kernel.org/r/20230411054543.21278-9-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust')
-rw-r--r--rust/bindings/bindings_helper.h1
-rw-r--r--rust/helpers.c19
-rw-r--r--rust/kernel/lib.rs1
-rw-r--r--rust/kernel/task.rs75
4 files changed, 96 insertions, 0 deletions
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 75d85bd6c592..03656a44a83f 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -8,6 +8,7 @@
#include <linux/slab.h>
#include <linux/refcount.h>
+#include <linux/sched.h>
/* `bindgen` gets confused at certain things. */
const gfp_t BINDINGS_GFP_KERNEL = GFP_KERNEL;
diff --git a/rust/helpers.c b/rust/helpers.c
index 446e3cfdb935..6e5b2c953d36 100644
--- a/rust/helpers.c
+++ b/rust/helpers.c
@@ -24,6 +24,7 @@
#include <linux/refcount.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
+#include <linux/sched/signal.h>
__noreturn void rust_helper_BUG(void)
{
@@ -60,6 +61,12 @@ void rust_helper_spin_unlock(spinlock_t *lock)
}
EXPORT_SYMBOL_GPL(rust_helper_spin_unlock);
+int rust_helper_signal_pending(struct task_struct *t)
+{
+ return signal_pending(t);
+}
+EXPORT_SYMBOL_GPL(rust_helper_signal_pending);
+
refcount_t rust_helper_REFCOUNT_INIT(int n)
{
return (refcount_t)REFCOUNT_INIT(n);
@@ -96,6 +103,18 @@ long rust_helper_PTR_ERR(__force const void *ptr)
}
EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR);
+void rust_helper_get_task_struct(struct task_struct *t)
+{
+ get_task_struct(t);
+}
+EXPORT_SYMBOL_GPL(rust_helper_get_task_struct);
+
+void rust_helper_put_task_struct(struct task_struct *t)
+{
+ put_task_struct(t);
+}
+EXPORT_SYMBOL_GPL(rust_helper_put_task_struct);
+
/*
* We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type
* as the Rust `usize` type, so we can use it in contexts where Rust
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 2d7606135ef6..ee27e10da479 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -44,6 +44,7 @@ mod static_assert;
pub mod std_vendor;
pub mod str;
pub mod sync;
+pub mod task;
pub mod types;
#[doc(hidden)]
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
new file mode 100644
index 000000000000..d70cad131956
--- /dev/null
+++ b/rust/kernel/task.rs
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Tasks (threads and processes).
+//!
+//! C header: [`include/linux/sched.h`](../../../../include/linux/sched.h).
+
+use crate::{bindings, types::Opaque};
+use core::ptr;
+
+/// Wraps the kernel's `struct task_struct`.
+///
+/// # Invariants
+///
+/// All instances are valid tasks created by the C portion of the kernel.
+///
+/// Instances of this type are always ref-counted, that is, a call to `get_task_struct` ensures
+/// that the allocation remains valid at least until the matching call to `put_task_struct`.
+#[repr(transparent)]
+pub struct Task(pub(crate) Opaque<bindings::task_struct>);
+
+// SAFETY: It's OK to access `Task` through references from other threads because we're either
+// accessing properties that don't change (e.g., `pid`, `group_leader`) or that are properly
+// synchronised by C code (e.g., `signal_pending`).
+unsafe impl Sync for Task {}
+
+/// The type of process identifiers (PIDs).
+type Pid = bindings::pid_t;
+
+impl Task {
+ /// Returns the group leader of the given task.
+ pub fn group_leader(&self) -> &Task {
+ // SAFETY: By the type invariant, we know that `self.0` is a valid task. Valid tasks always
+ // have a valid group_leader.
+ let ptr = unsafe { *ptr::addr_of!((*self.0.get()).group_leader) };
+
+ // SAFETY: The lifetime of the returned task reference is tied to the lifetime of `self`,
+ // and given that a task has a reference to its group leader, we know it must be valid for
+ // the lifetime of the returned task reference.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Returns the PID of the given task.
+ pub fn pid(&self) -> Pid {
+ // SAFETY: By the type invariant, we know that `self.0` is a valid task. Valid tasks always
+ // have a valid pid.
+ unsafe { *ptr::addr_of!((*self.0.get()).pid) }
+ }
+
+ /// Determines whether the given task has pending signals.
+ pub fn signal_pending(&self) -> bool {
+ // SAFETY: By the type invariant, we know that `self.0` is valid.
+ unsafe { bindings::signal_pending(self.0.get()) != 0 }
+ }
+
+ /// Wakes up the task.
+ pub fn wake_up(&self) {
+ // SAFETY: By the type invariant, we know that `self.0.get()` is non-null and valid.
+ // And `wake_up_process` is safe to be called for any valid task, even if the task is
+ // running.
+ unsafe { bindings::wake_up_process(self.0.get()) };
+ }
+}
+
+// SAFETY: The type invariants guarantee that `Task` is always ref-counted.
+unsafe impl crate::types::AlwaysRefCounted for Task {
+ fn inc_ref(&self) {
+ // SAFETY: The existence of a shared reference means that the refcount is nonzero.
+ unsafe { bindings::get_task_struct(self.0.get()) };
+ }
+
+ unsafe fn dec_ref(obj: ptr::NonNull<Self>) {
+ // SAFETY: The safety requirements guarantee that the refcount is nonzero.
+ unsafe { bindings::put_task_struct(obj.cast().as_ptr()) }
+ }
+}