From: Alice Ryhl <aliceryhl@google.com>
To: benno.lossin@proton.me
Cc: a.hindborg@samsung.com, alex.gaynor@gmail.com,
aliceryhl@google.com, arve@android.com,
bjorn3_gh@protonmail.com, boqun.feng@gmail.com,
brauner@kernel.org, cmllamas@google.com,
dan.j.williams@intel.com, dxu@dxuuu.xyz, gary@garyguo.net,
gregkh@linuxfoundation.org, joel@joelfernandes.org,
keescook@chromium.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, maco@android.com,
ojeda@kernel.org, peterz@infradead.org,
rust-for-linux@vger.kernel.org, surenb@google.com,
tglx@linutronix.de, tkjos@android.com, viro@zeniv.linux.org.uk,
wedsonaf@gmail.com, willy@infradead.org
Subject: Re: [PATCH 6/7] rust: file: add `DeferredFdCloser`
Date: Fri, 1 Dec 2023 11:35:38 +0000 [thread overview]
Message-ID: <20231201113538.2202170-1-aliceryhl@google.com> (raw)
In-Reply-To: <LNSA8EeuwLGDBzY1W8GaP1L6gucAPE_34myHWuyg3ziYuheiFLk3WfVBPppzwDZwoGVTCqL8EBjAaxsNshTY6AQq_sNtK9hmea7FeaNJuCo=@proton.me>
Benno Lossin <benno.lossin@proton.me> writes:
>> + // SAFETY: The `inner` pointer points at a valid and fully initialized task work that is
>> + // ready to be scheduled.
>> + unsafe { bindings::task_work_add(current, inner, TWA_RESUME) };
>
> I am a bit confused, when does `do_close_fd` actually run? Does
> `TWA_RESUME` mean that `inner` is scheduled to run after the current
> task has been completed?
When the current syscall returns to userspace.
>> + // SAFETY: This function is an implementation detail of `close_fd`, so its safety comments
>> + // should be read in extension of that method.
>> + unsafe extern "C" fn do_close_fd(inner: *mut bindings::callback_head) {
>> + // SAFETY: In `close_fd` we use this method together with a pointer that originates from a
>> + // `Box<DeferredFdCloserInner>`, and we have just been given ownership of that allocation.
>> + let inner = unsafe { Box::from_raw(inner as *mut DeferredFdCloserInner) };
>
> In order for this call to be sound, `inner` must be an exclusive
> pointer (including any possible references into the `callback_head`).
> Is this the case?
Yes, when this is called, it's been removed from the linked list of task
work. That's why we can kfree it.
>> + // SAFETY: Since `DeferredFdCloserInner` is `#[repr(C)]`, casting the pointers gives a
>> + // pointer to the `twork` field.
>> + let inner = Box::into_raw(self.inner) as *mut bindings::callback_head;
>
> Here you can just use `.cast::<...>()`.
Will do.
Alice
next prev parent reply other threads:[~2023-12-01 11:35 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-29 12:51 [PATCH 0/7] File abstractions needed by Rust Binder Alice Ryhl
2023-11-29 12:51 ` [PATCH 1/7] rust: file: add Rust abstraction for `struct file` Alice Ryhl
2023-11-29 15:13 ` Matthew Wilcox
2023-11-29 15:23 ` Peter Zijlstra
2023-11-29 17:08 ` Boqun Feng
2023-11-30 10:42 ` Peter Zijlstra
2023-11-30 15:25 ` Boqun Feng
2023-12-01 8:53 ` Peter Zijlstra
2023-12-01 9:19 ` Boqun Feng
2023-12-01 9:40 ` Peter Zijlstra
2023-12-01 10:36 ` Boqun Feng
2023-12-01 11:05 ` Peter Zijlstra
2023-12-01 9:00 ` Peter Zijlstra
2023-12-01 9:52 ` Boqun Feng
2023-11-29 16:42 ` Alice Ryhl
2023-11-29 16:45 ` Peter Zijlstra
2023-11-30 15:02 ` Benno Lossin
2023-11-29 17:06 ` Christian Brauner
2023-11-29 21:27 ` Alice Ryhl
2023-11-29 23:17 ` Benno Lossin
2023-11-30 10:48 ` Christian Brauner
2023-11-30 12:10 ` Alice Ryhl
2023-11-30 12:36 ` Christian Brauner
2023-11-30 14:53 ` Benno Lossin
2023-11-30 14:59 ` Greg Kroah-Hartman
2023-11-30 15:46 ` Benno Lossin
2023-11-30 15:56 ` Greg Kroah-Hartman
2023-11-30 15:58 ` Theodore Ts'o
2023-11-30 16:12 ` Benno Lossin
2023-12-01 1:16 ` Theodore Ts'o
2023-12-01 12:11 ` David Laight
2023-12-01 12:27 ` Alice Ryhl
2023-12-01 15:04 ` Theodore Ts'o
2023-12-01 15:14 ` Benno Lossin
2023-12-01 17:25 ` David Laight
2023-12-01 17:37 ` Benno Lossin
2023-11-29 12:51 ` [PATCH 2/7] rust: cred: add Rust abstraction for `struct cred` Alice Ryhl
2023-11-30 16:17 ` Benno Lossin
2023-12-01 9:06 ` Alice Ryhl
2023-12-01 10:27 ` Christian Brauner
2023-12-04 15:42 ` Alice Ryhl
2023-11-29 13:11 ` [PATCH 3/7] rust: security: add abstraction for secctx Alice Ryhl
2023-11-30 16:26 ` Benno Lossin
2023-12-01 10:48 ` Alice Ryhl
2023-12-02 10:03 ` Benno Lossin
2023-11-29 13:11 ` [PATCH 4/7] rust: file: add `FileDescriptorReservation` Alice Ryhl
2023-11-29 16:14 ` Christian Brauner
2023-11-29 16:55 ` Alice Ryhl
2023-11-29 17:14 ` Alice Ryhl
2023-11-30 9:12 ` Christian Brauner
2023-11-30 9:23 ` Alice Ryhl
2023-11-30 9:09 ` Christian Brauner
2023-11-30 9:17 ` Alice Ryhl
2023-11-30 10:51 ` Christian Brauner
2023-11-30 11:54 ` Alice Ryhl
2023-11-30 12:17 ` Benno Lossin
2023-11-30 12:33 ` Christian Brauner
2023-11-30 16:40 ` Benno Lossin
2023-12-01 11:32 ` Alice Ryhl
2023-11-29 13:12 ` [PATCH 5/7] rust: file: add `Kuid` wrapper Alice Ryhl
2023-11-29 16:28 ` Christian Brauner
2023-11-29 16:48 ` Peter Zijlstra
2023-11-30 12:46 ` Christian Brauner
2023-12-06 19:59 ` Kent Overstreet
2023-12-08 16:26 ` Peter Zijlstra
2023-12-08 19:58 ` Kent Overstreet
2023-12-08 5:28 ` comex
2023-12-08 16:19 ` Miguel Ojeda
2023-12-08 17:08 ` Nick Desaulniers
2023-12-08 17:37 ` Miguel Ojeda
2023-12-08 17:43 ` Boqun Feng
2023-12-08 20:43 ` Matthew Wilcox
2023-12-09 7:24 ` comex
2023-11-30 9:36 ` Alice Ryhl
2023-11-30 10:52 ` Christian Brauner
2023-11-30 10:36 ` Peter Zijlstra
2023-12-06 20:02 ` Kent Overstreet
2023-12-07 7:18 ` Greg Kroah-Hartman
2023-12-07 7:46 ` Kent Overstreet
2023-11-30 16:48 ` Benno Lossin
2023-11-29 13:12 ` [PATCH 6/7] rust: file: add `DeferredFdCloser` Alice Ryhl
2023-11-30 17:12 ` Benno Lossin
2023-12-01 11:35 ` Alice Ryhl [this message]
2023-12-02 10:16 ` Benno Lossin
2023-12-05 14:43 ` Alice Ryhl
2023-12-05 18:16 ` Alice Ryhl
2023-11-29 13:12 ` [PATCH 7/7] rust: file: add abstraction for `poll_table` Alice Ryhl
2023-11-30 17:42 ` Benno Lossin
2023-12-01 11:47 ` Alice Ryhl
2023-11-30 22:39 ` Boqun Feng
2023-12-01 11:50 ` Alice Ryhl
2023-11-30 22:50 ` Boqun Feng
2023-11-29 16:31 ` [PATCH 0/7] File abstractions needed by Rust Binder Christian Brauner
2023-11-29 16:48 ` Miguel Ojeda
2023-12-06 20:05 ` Kent Overstreet
2023-12-08 16:59 ` Miguel Ojeda
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