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printk: Use prb_first_seq() as base for 32bit seq macros 

[ Upstream commit 90ad525c2d ]

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>
Link: https://lore.kernel.org/r/20240207134103.1357162-4-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
John Ogness 2024-02-07 14:46:52 +01:06 committed by Sasha Levin
parent 7c09db1068
commit 3a2bd2b150
2 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/printk/printk_ringbuffer.c
View File

@ -1931,7 +1931,7 @@ 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;

8
kernel/printk/printk_ringbuffer.h
View File

@ -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);
u64 prb_next_reserve_seq(struct printk_ringbuffer *rb);
@ -393,12 +394,12 @@ u64 prb_next_reserve_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.
@ -407,8 +408,7 @@ 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;
}