This is a note to let you know that I've just added the patch titled
printk: Use prb_first_seq() as base for 32bit seq macros
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
printk-use-prb_first_seq-as-base-for-32bit-seq-macro.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ee5d170bb8a0be2ff1776ba8c9d004eb750b9616
Author: John Ogness <john.ogness@xxxxxxxxxxxxx>
Date: Wed Feb 7 14:46:52 2024 +0106
printk: Use prb_first_seq() as base for 32bit seq macros
[ Upstream commit 90ad525c2d9a8a6591ab822234a94b82871ef8e0 ]
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@xxxxxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Link: https://lore.kernel.org/r/20240207134103.1357162-4-john.ogness@xxxxxxxxxxxxx
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c
index 3d98232902cfd..f5a8bb606fe50 100644
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -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;
diff --git a/kernel/printk/printk_ringbuffer.h b/kernel/printk/printk_ringbuffer.h
index d729387726900..cb887489d00f0 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);
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;
}
