[PATCH printk v4 03/14] printk: Use prb_first_seq() as base for 32bit seq macros

John Ogness
2024-02-07T13:41:16Z

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>
Reviewed-by: Petr Mladek <pmladek@suse.com>
---
kernel/printk/printk_ringbuffer.c | 2 +-
kernel/printk/printk_ringbuffer.h | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c
index fde338606ce8..49a82ccce8e9 100644
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -1832,7 +1832,7 @@ static int prb_read(struct printk_ringbuffer *rb, u64 seq,
}

/* 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;
diff --git a/kernel/printk/printk_ringbuffer.h b/kernel/printk/printk_ringbuffer.h
index 12f60c782e46..ee294aaf4aeb 100644
--- a/kernel/printk/printk_ringbuffer.h
+++ b/kernel/printk/printk_ringbuffer.h
@@ -378,6 +378,7 @@ bool prb_read_valid(struct printk_ringbuffer *rb, u64 seq,
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_ringbuffer *rb);

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(struct printk_ringbuffer *rb, u32 ulseq)
*
* 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;
}
--
2.39.2