Steps on the way to 6.12.20
Resolves merge conflicts in:
rust/kernel/sync.rs
Change-Id: I2e13aa71c635af1cbbc66a28b113bb43c4b16053
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
The new `shmem.rs` file is a Rust abstraction around shmem files. It's
important that we modify the fops to prevent users from calling mmap
again, as they could otherwise modify the protection bits on the memory
region in a way that bypasses the ashmem protection mask.
Bug: 370906207
Change-Id: I0d2f4b56ac005d131a6ef0f9c7b346549effd1d7
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Add support for creating global variables that are wrapped in a mutex or
spinlock.
The implementation here is intended to replace the global mutex
workaround found in the Rust Binder RFC [1]. In both cases, the global
lock must be initialized before first use. The macro is unsafe to use
for the same reason.
The separate initialization step is required because it is tricky to
access the value of __ARCH_SPIN_LOCK_UNLOCKED from Rust. Doing so will
require changes to the C side. That change will happen as a follow-up to
this patch.
Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-2-08ba9197f637@google.com/#Z31drivers:android:context.rs [1]
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241023-static-mutex-v6-1-d7efdadcc84f@google.com
[ Simplified a few intra-doc links. Formatted a few comments. Reworded
title. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Bug: 370906207
Change-Id: Ic37c2ec834ab0a506cef15e8fd4c6be63766331b
(cherry picked from commit 8eea62ff94f4dbad8ee884b0b33202e0a0fb350b)
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
The existing `CondVar` abstraction is a wrapper around
`wait_queue_head`, but it does not support all use-cases of the C
`wait_queue_head` type. To be specific, a `CondVar` cannot be registered
with a `struct poll_table`. This limitation has the advantage that you
do not need to call `synchronize_rcu` when destroying a `CondVar`.
However, we need the ability to register a `poll_table` with a
`wait_queue_head` in Rust Binder. To enable this, introduce a type
called `PollCondVar`, which is like `CondVar` except that you can
register a `poll_table`. We also introduce `PollTable`, which is a safe
wrapper around `poll_table` that is intended to be used with
`PollCondVar`.
The destructor of `PollCondVar` unconditionally calls `synchronize_rcu`
to ensure that the removal of epoll waiters has fully completed before
the `wait_queue_head` is destroyed.
That said, `synchronize_rcu` is rather expensive and is not needed in
all cases: If we have never registered a `poll_table` with the
`wait_queue_head`, then we don't need to call `synchronize_rcu`. (And
this is a common case in Binder - not all processes use Binder with
epoll.) The current implementation does not account for this, but if we
find that it is necessary to improve this, a future patch could store a
boolean next to the `wait_queue_head` to keep track of whether a
`poll_table` has ever been registered.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-8-88484f7a3dcf@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Bug: 370906207
(cherry picked from commit ac681835b6747fc5a0cd40398d4c28210318df32)
Change-Id: I41bddb75869e4872de1d01df8635235fb9549bdf
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Currently, all macros are reexported with #[macro_export] only, which
means that to access `new_work!` from the workqueue, you need to import
it from the path `kernel::new_work` instead of importing it from the
workqueue module like all other items in the workqueue. By adding
reexports of the macros, it becomes possible to import the macros from
the correct modules.
It's still possible to import the macros from the root, but I don't
think we can do anything about that.
There is no functional change. This is merely a code cleanliness
improvement.
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20240129145837.1419880-1-aliceryhl@google.com
[ Removed new `use kernel::prelude::*`s, reworded title. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Sleep on a condition variable with a timeout.
This is used by Rust Binder for process freezing. There, we want to
sleep until the freeze operation completes, but we want to be able to
abort the process freezing if it doesn't complete within some timeout.
Note that it is not enough to avoid jiffies by introducing a variant of
`CondVar::wait_timeout` that takes the timeout in msecs because we need
to be able to restart the sleep with the remaining sleep duration if it
is interrupted, and if the API takes msecs rather than jiffies, then
that would require a conversion roundtrip jiffies->msecs->jiffies that
is best avoided.
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Tiago Lam <tiagolam@gmail.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20240108-rb-new-condvar-methods-v4-3-88e0c871cc05@google.com
[ Added `CondVarTimeoutResult` re-export and fixed typo. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Since `Arc<T>` does not allow mutating `T` directly (i.e., without inner
mutability), it is currently not possible to do some initialisation of
`T` post construction but before being shared.
`UniqueArc<T>` addresses this problem essentially being an `Arc<T>` that
has a refcount of 1 and is therefore writable. Once initialisation is
completed, it can be transitioned (without failure paths) into an
`Arc<T>`.
Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
