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McKenney" Cc: Gary Guo , Greg Kroah-Hartman , Carlos Llamas , linux-fsdevel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Alice Ryhl Content-Type: text/plain; charset="utf-8" Right now Rust Binder calls synchronize_rcu() more often than is necessary. Most processes do not use epoll at all, so they don't require rcu here. Back in Kangrejos I came up with a way to avoid this. Idea is to move the value that needs rcu to a separate allocation that's easy to kfree_rcu(). We pay the allocation only when the proc uses epoll using an "upgrade" strategy - most processes don't. One solution that may be better is to just kfree_rcu() the Binder Thread struct directly when it's refcount drops to zero (Drop of everything else can still run without a grace period). But I'm not sure how I would achieve that - after all Thread is also used with kernel::list. Signed-off-by: Alice Ryhl --- Changes in v2: - Change how Rust Binder handles the lock class key. - Rebase. - Link to v1: https://lore.kernel.org/r/20260117-upgrade-poll-v1-0-179437b7bd49@google.com --- Alice Ryhl (2): rust: poll: make PollCondVar upgradable rust_binder: use UpgradePollCondVar drivers/android/binder/process.rs | 2 +- drivers/android/binder/thread.rs | 25 +++--- rust/kernel/sync/poll.rs | 160 +++++++++++++++++++++++++++++++++++++- 3 files changed, 176 insertions(+), 11 deletions(-) --- base-commit: de718b2ca866e10e2a26c259ab0493a5af411879 change-id: 20260117-upgrade-poll-37ee2a7a79dd Best regards, -- Alice Ryhl