[PATCH] rust_binder: speed up get_node_debug_info using lower_bound iter

Finding the next node in the RBTree can be done more efficiently using
the cursor_lower_bound, as it reduces cost from O(n) to O(log n).

Link: https://github.com/Rust-for-Linux/linux/issues/1249
Suggested-by: Alice Ryhl <[email protected]>
Signed-off-by: Rafael Passos <[email protected]>
---

(Sorry for the resend, my script missed the list)

Hi, I decided to use the peek_next semantic instead of a loop/break.
Since the iterator should land directly on ptr or greater, I think this
is more elegant this way. But I can change it otherwise.

Thanks,
Rafael


 drivers/android/binder/process.rs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/android/binder/process.rs b/drivers/android/binder/process.rs
index cdd1a90797266..c0c2112aca1c6 100644
--- a/drivers/android/binder/process.rs
+++ b/drivers/android/binder/process.rs
@@ -1174,10 +1174,15 @@ fn get_node_debug_info(&self, data: UserSlice) -> Result {
 
         {
             let inner = self.inner.lock();
-            for (node_ptr, node) in &inner.nodes {
+            let cursor = inner.nodes.cursor_lower_bound(&ptr);
+            if let Some(c) = cursor {
+                let (node_ptr, node) = c.current();
                 if *node_ptr > ptr {
                     node.populate_debug_info(&mut out, &inner);
-                    break;
+                } else if *node_ptr == ptr {
+                    if let Some((_, next_node)) = c.peek_next() {
+                        next_node.populate_debug_info(&mut out, &inner);
+                    }
                 }
             }
         }
-- 
2.53.0