rust: poll: use kfree_rcu() for PollCondVar

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Rust Binder currently uses PollCondVar, but it calls synchronize_rcu()
in the destructor, which we would like to avoid. Add a variation of
PollCondVar that kfree_rcu() instead.

One could avoid the `rcu` field and allocate the rcu_head on drop using
a fallback to synchronize_rcu() on ENOMEM. However, I'd prefer to avoid
the potential for synchronize_rcu(), and Binder will only use this for a
small fraction of processes, so even if it changes which kmalloc bucket
it falls into, the extra memory is not a problem.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun@kernel.org>
Link: https://patch.msgid.link/20260707-upgrade-poll-v6-1-4b8fae7bf1d9@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Alice Ryhl 2026-07-07 10:43:12 +00:00 • committed by Greg Kroah-Hartman

parent f14e0c8183

commit e5e86df8b6

1 changed files with 72 additions and 1 deletions

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rust/kernel/sync/poll.rs

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