From 8df412aa1715bcbf31276e8ac55047a18b48fdf9 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Mon, 20 Nov 2023 15:06:57 +0100 Subject: [PATCH 151/184] printk/ringbuffer: Extend the sequence number properly on 32bit. The sequence number on 32bit platform is extendend to a full 64bit variable from a 32bit value and a 64bit previous record. The formala as-is is okay but it relies on the right part to be negative which is not the case if the result is a unsigned variable. Cast the result to a signed variable. Reported-by: Francesco Dolcini Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202311171611.78d41dbe-oliver.sang@intel.com Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202311161555.3ee16fc9-oliver.sang@intel.com Signed-off-by: Sebastian Andrzej Siewior --- kernel/printk/printk_ringbuffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c index a949d02fbd17..2b2a85222d19 100644 --- a/kernel/printk/printk_ringbuffer.c +++ b/kernel/printk/printk_ringbuffer.c @@ -1477,7 +1477,7 @@ static inline u64 __ulseq_to_u64seq(u32 ulseq) * sequence. It needs to be expanded to 64bit. Get the first sequence * number from the ringbuffer and fold it. */ - seq = rb_first_seq - ((u32)rb_first_seq - ulseq); + seq = rb_first_seq - ((s32)((u32)rb_first_seq - ulseq)); return seq; } -- 2.34.1