linux-kernel - [PATCH v2 2/2] printk_ringbuffer: allow one data block to occupy the entire data ring

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Message-Id: <20250905144152.9137-3-d-tatianin@yandex-team.ru>
Date: Fri,  5 Sep 2025 17:41:52 +0300
From: Daniil Tatianin <d-tatianin@...dex-team.ru>
To: Petr Mladek <pmladek@...e.com>
Cc: Daniil Tatianin <d-tatianin@...dex-team.ru>,
	linux-kernel@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH v2 2/2] printk_ringbuffer: allow one data block to occupy the entire data ring

We no longer require a trailing id at the end of the data ring, so
there is no reason to check that one fits.

Signed-off-by: Daniil Tatianin <d-tatianin@...dex-team.ru>
---
 kernel/printk/printk_ringbuffer.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c
index 99989a9ce4b4..cbbd356b085b 100644
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -397,21 +397,14 @@ static unsigned int to_blk_size(unsigned int size)
  */
 static bool data_check_size(struct prb_data_ring *data_ring, unsigned int size)
 {
-	struct prb_data_block *db = NULL;
-
 	if (size == 0)
 		return true;
 
 	/*
 	 * Ensure the alignment padded size could possibly fit in the data
-	 * array. The largest possible data block must still leave room for
-	 * at least the ID of the next block.
+	 * array.
 	 */
-	size = to_blk_size(size);
-	if (size > DATA_SIZE(data_ring) - sizeof(db->id))
-		return false;
-
-	return true;
+	return (to_blk_size(size) <= DATA_SIZE(data_ring));
 }
 
 /* Query the state of a descriptor. */
-- 
2.43.0