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From: John Ogness <john.ogness@linutronix.de>
Date: Wed, 22 Nov 2023 16:13:37 +0000
Subject: [PATCH 03/50] printk: Use prb_first_seq() as base for 32bit seq
macros
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.7/older/patches-6.7-rt6.tar.xz
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(-)
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -1832,7 +1832,7 @@ 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;
--- a/kernel/printk/printk_ringbuffer.h
+++ b/kernel/printk/printk_ringbuffer.h
@@ -378,6 +378,7 @@ 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);
@@ -392,12 +393,12 @@ 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.
@@ -406,8 +407,7 @@ 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;
}
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