linux-kernel - [PATCH v2 21/28] binder: make oversized buffer code more readable

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Message-ID: <20231201172212.1813387-22-cmllamas@google.com>
Date:   Fri,  1 Dec 2023 17:21:50 +0000
From:   Carlos Llamas <cmllamas@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Arve Hjønnevåg" <arve@...roid.com>,
        Todd Kjos <tkjos@...roid.com>,
        Martijn Coenen <maco@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Christian Brauner <brauner@...nel.org>,
        Carlos Llamas <cmllamas@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kernel-team@...roid.com
Subject: [PATCH v2 21/28] binder: make oversized buffer code more readable

The sections in binder_alloc_new_buf_locked() dealing with oversized
buffers are scattered which makes them difficult to read. Instead,
consolidate this code into a single block to improve readability.

No functional change here.

Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
---
 drivers/android/binder_alloc.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index c9292eee8fee..ad9b73c6ddb7 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -483,32 +483,31 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
 		goto out;
 	}
 
-	if (n == NULL) {
+	if (buffer_size != size) {
+		/* Found an oversized buffer and needs to be split */
 		buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
+
+		WARN_ON(n || buffer_size == size);
+		new_buffer->user_data = buffer->user_data + size;
+		list_add(&new_buffer->entry, &buffer->entry);
+		new_buffer->free = 1;
+		binder_insert_free_buffer(alloc, new_buffer);
+		new_buffer = NULL;
 	}
 
 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 		     "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
 		      alloc->pid, size, buffer, buffer_size);
 
-	WARN_ON(n && buffer_size != size);
-
 	has_page_addr = (buffer->user_data + buffer_size) & PAGE_MASK;
 	end_page_addr = PAGE_ALIGN(buffer->user_data + size);
 	if (end_page_addr > has_page_addr)
 		end_page_addr = has_page_addr;
 	binder_allocate_page_range(alloc, PAGE_ALIGN(buffer->user_data),
 				   end_page_addr);
-	if (buffer_size != size) {
-		new_buffer->user_data = buffer->user_data + size;
-		list_add(&new_buffer->entry, &buffer->entry);
-		new_buffer->free = 1;
-		binder_insert_free_buffer(alloc, new_buffer);
-		new_buffer = NULL;
-	}
 
-	rb_erase(best_fit, &alloc->free_buffers);
+	rb_erase(&buffer->rb_node, &alloc->free_buffers);
 	buffer->free = 0;
 	buffer->allow_user_free = 0;
 	binder_insert_allocated_buffer_locked(alloc, buffer);
-- 
2.43.0.rc2.451.g8631bc7472-goog