[Crash-utility] [PATCH] printk: add support for lockless ringbuffer

[HAGIO KAZUHITO(萩尾 一仁)]

Hi,

Merged the two patches.
https://github.com/crash-utility/crash/compare/bf57c44...71e159c

John, thank you very much for taking care of the userspace tools!

Kazu

-----Original Message-----
> -----Original Message-----
> > 在 2020年11月20日 13:56, HAGIO KAZUHITO(萩尾　一仁) 写道:
> > > From: John Ogness <john.ogness at linutronix.de>
> > >
> > > Linux 5.10 introduces a new lockless ringbuffer. The new ringbuffer
> > > is structured completely different to the previous iterations.
> > > Add support for dumping the ringbuffer with the "log" command.
> > > The new ringbuffer is detected based on the availability of
> > > the "prb" symbol.
> > >
> > > Signed-off-by: John Ogness <john.ogness at linutronix.de>
> > > Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
> > > ---
> > > I've updated John's RFC crash patch to match 5.10-rc4 kernel.
> > > Changes from the RFC patch:
> > > - followed the following kernel commits
> > >     cfe2790b163a ("printk: move printk_info into separate array")
> > >     74caba7f2a06 ("printk: move dictionary keys to dev_printk_info")
> > >     f35efc78add6 ("printk: remove dict ring")
> > > - moved the added members in offset_table and size_table to the end
> > >   of them
> > > - print offsets and sizes with "help -o" option
> > > - support "log -T" option
> > >
> >
> > Thanks for the patch, Kazu and John.
> >
> > This patch looks good. Acked-by: Lianbo Jiang <lijiang at redhat.com>
> 
> OK, thanks.
> 
> One thing, I found that caller_id can be raw_smp_processor_id() (see
> printk_caller_id()), so will modify a bit as follows when merging.
> 
> --- a/printk.c
> +++ b/printk.c
> @@ -132,7 +132,8 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags)
>         seq = ULONGLONG(info + OFFSET(printk_info_seq));
>         caller_id = UINT(info + OFFSET(printk_info_caller_id));
>         if (CRASHDEBUG(1))
> -               fprintf(fp, "seq: %llu caller_id: %u\n", seq, caller_id);
> +               fprintf(fp, "seq: %llu caller_id: %x (%s: %u)\n", seq, caller_id,
> +                       caller_id & 0x80000000 ? "cpu" : "pid", caller_id & ~0x80000000);
> 
>         text_len = USHORT(info + OFFSET(printk_info_text_len));
> 
> Thanks,
> Kazu
>