From 1781fbdda677525b2e7fa536c7d7618637bb8c68 Mon Sep 17 00:00:00 2001
From: John Ogness <john.ogness@linutronix.de>
Date: Wed, 22 Nov 2023 16:13:37 +0000
Subject: [PATCH 113/204] printk: Use prb_first_seq() as base for 32bit seq
 macros

Note: This change only applies to 32bit architectures. On 64bit
      architectures the macros are NOPs.

Currently prb_next_seq() is used as the base for the 32bit seq
macros __u64seq_to_ulseq() and __ulseq_to_u64seq(). However, in
a follow-up commit, prb_next_seq() will need to make use of the
32bit seq macros.

Use prb_first_seq() as the base for the 32bit seq macros instead
because it is guaranteed to return 64bit sequence numbers without
relying on any 32bit seq macros.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/printk/printk_ringbuffer.c |    2 +-
 kernel/printk/printk_ringbuffer.h |    8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

Index: linux-6.6.58-rt45/kernel/printk/printk_ringbuffer.c
===================================================================
@ linux-6.6.58-rt45/kernel/printk/printk_ringbuffer.c:1835 @ static int prb_read(struct printk_ringbu
 }
 
 /* Get the sequence number of the tail descriptor. */
-static u64 prb_first_seq(struct printk_ringbuffer *rb)
+u64 prb_first_seq(struct printk_ringbuffer *rb)
 {
 	struct prb_desc_ring *desc_ring = &rb->desc_ring;
 	enum desc_state d_state;
Index: linux-6.6.58-rt45/kernel/printk/printk_ringbuffer.h
===================================================================
--- linux-6.6.58-rt45.orig/kernel/printk/printk_ringbuffer.h
+++ linux-6.6.58-rt45/kernel/printk/printk_ringbuffer.h
@ linux-6.6.58-rt45/kernel/printk/printk_ringbuffer.c:381 @ bool prb_read_valid(struct printk_ringbu
 bool prb_read_valid_info(struct printk_ringbuffer *rb, u64 seq,
 			 struct printk_info *info, unsigned int *line_count);
 
+u64 prb_first_seq(struct printk_ringbuffer *rb);
 u64 prb_first_valid_seq(struct printk_ringbuffer *rb);
 u64 prb_next_seq(struct printk_ringbuffer *rb);
 
@ linux-6.6.58-rt45/kernel/printk/printk_ringbuffer.c:396 @ u64 prb_next_seq(struct printk_ringbuffe
 
 static inline u64 __ulseq_to_u64seq(struct printk_ringbuffer *rb, u32 ulseq)
 {
+	u64 rb_first_seq = prb_first_seq(rb);
 	u64 seq;
-	u64 rb_next_seq;
 
 	/*
 	 * The provided sequence is only the lower 32 bits of the ringbuffer
-	 * sequence. It needs to be expanded to 64bit. Get the next sequence
+	 * sequence. It needs to be expanded to 64bit. Get the first sequence
 	 * number from the ringbuffer and fold it.
 	 *
 	 * Having a 32bit representation in the console is sufficient.
@ linux-6.6.58-rt45/kernel/printk/printk_ringbuffer.c:410 @ static inline u64 __ulseq_to_u64seq(stru
 	 *
 	 * Also the access to the ring buffer is always safe.
 	 */
-	rb_next_seq = prb_next_seq(rb);
-	seq = rb_next_seq - (s32)((u32)rb_next_seq - ulseq);
+	seq = rb_first_seq - (s32)((u32)rb_first_seq - ulseq);
 
 	return seq;
 }