The following commit has been merged into the locking/core branch of tip: Commit-ID: 70b9c8563c9c29102a785d4822f0d77d33fee808 Gitweb: https://git.kernel.org/tip/70b9c8563c9c29102a785d4822f0d77d33fee808 Author: Alice Ryhl <aliceryhl@xxxxxxxxxx> AuthorDate: Fri, 07 Mar 2025 15:26:59 -08:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Sat, 08 Mar 2025 00:55:04 +01:00 rust: sync: condvar: Add wait_interruptible_freezable() To support waiting for a `CondVar` as a freezable process, add a wait_interruptible_freezable() function. Binder needs this function in the appropriate places to freeze a process where some of its threads are blocked on the Binder driver. [ Boqun: Cleaned up the changelog and documentation. ] Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20250307232717.1759087-10-boqun.feng@xxxxxxxxx --- rust/kernel/sync/condvar.rs | 23 ++++++++++++++++++++++- rust/kernel/task.rs | 2 ++ 2 files changed, 24 insertions(+), 1 deletion(-) diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs index 7df5650..5c1e546 100644 --- a/rust/kernel/sync/condvar.rs +++ b/rust/kernel/sync/condvar.rs @@ -11,7 +11,9 @@ use crate::{ init::PinInit, pin_init, str::CStr, - task::{MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE, TASK_NORMAL, TASK_UNINTERRUPTIBLE}, + task::{ + MAX_SCHEDULE_TIMEOUT, TASK_FREEZABLE, TASK_INTERRUPTIBLE, TASK_NORMAL, TASK_UNINTERRUPTIBLE, + }, time::Jiffies, types::Opaque, }; @@ -159,6 +161,25 @@ impl CondVar { crate::current!().signal_pending() } + /// Releases the lock and waits for a notification in interruptible and freezable mode. + /// + /// The process is allowed to be frozen during this sleep. No lock should be held when calling + /// this function, and there is a lockdep assertion for this. Freezing a task that holds a lock + /// can trivially deadlock vs another task that needs that lock to complete before it too can + /// hit freezable. + #[must_use = "wait_interruptible_freezable returns if a signal is pending, so the caller must check the return value"] + pub fn wait_interruptible_freezable<T: ?Sized, B: Backend>( + &self, + guard: &mut Guard<'_, T, B>, + ) -> bool { + self.wait_internal( + TASK_INTERRUPTIBLE | TASK_FREEZABLE, + guard, + MAX_SCHEDULE_TIMEOUT, + ); + crate::current!().signal_pending() + } + /// Releases the lock and waits for a notification in interruptible mode. /// /// Atomically releases the given lock (whose ownership is proven by the guard) and puts the diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs index 07bc22a..ea43a3b 100644 --- a/rust/kernel/task.rs +++ b/rust/kernel/task.rs @@ -23,6 +23,8 @@ pub const MAX_SCHEDULE_TIMEOUT: c_long = c_long::MAX; pub const TASK_INTERRUPTIBLE: c_int = bindings::TASK_INTERRUPTIBLE as c_int; /// Bitmask for tasks that are sleeping in an uninterruptible state. pub const TASK_UNINTERRUPTIBLE: c_int = bindings::TASK_UNINTERRUPTIBLE as c_int; +/// Bitmask for tasks that are sleeping in a freezable state. +pub const TASK_FREEZABLE: c_int = bindings::TASK_FREEZABLE as c_int; /// Convenience constant for waking up tasks regardless of whether they are in interruptible or /// uninterruptible sleep. pub const TASK_NORMAL: c_uint = bindings::TASK_NORMAL as c_uint;
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