From: John Ogness Date: Wed, 22 Nov 2023 16:13:37 +0000 Subject: [PATCH 087/134] printk: Use prb_first_seq() as base for 32bit seq macros Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.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 Signed-off-by: Sebastian Andrzej Siewior --- 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; }