[PATCH v3] vmcore-dmesg: Collect full dmesg regardless of logged_chars

[Dave Young]

On 11/18/15 at 01:24pm, Dangyi Liu wrote:
> Simon,
> 
> Could you help to review this patch?
> 
> Thanks,
> Dangyi Liu
> 
> On Wed, 2015-10-28 at 17:15 +0800, Dangyi Liu wrote:
> > logged_chars would be set to 0 by `dmesg -c`, but full dmesg is
> > useful
> > for debugging. So instead of using logged_chars directly, we
> > calculate
> > it by ourselves.
> > 
> > Now logged_chars is set to the minimum of log_end and log_buf_len, as
> > the same logic as crash utility is using.
> > 
> > Signed-off-by: Dangyi Liu <dliu at redhat.com>
> > Cc: Dave Young <dyoung at redhat.com>
> > ---
> > Changes:
> >   v1->v2: Update comment and commit message.
> >   v2->v3: Adjust maximum line length
> > 
> >  vmcore-dmesg/vmcore-dmesg.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/vmcore-dmesg/vmcore-dmesg.c b/vmcore-dmesg/vmcore-
> > dmesg.c
> > index f47ee11..0364636 100644
> > --- a/vmcore-dmesg/vmcore-dmesg.c
> > +++ b/vmcore-dmesg/vmcore-dmesg.c
> > @@ -540,6 +540,12 @@ static void dump_dmesg_legacy(int fd)
> >  		exit(53);
> >  	}
> >  
> > +	/*
> > +	 * To collect full dmesg including the part before `dmesg
> > -c` is useful
> > +	 * for later debugging. Use same logic as what crash utility
> > is using.
> > +	 */
> > +	logged_chars = log_end < log_buf_len ? log_end :
> > log_buf_len;
> > +
> >  	write_to_stdout(buf + (log_buf_len -  logged_chars),
> > logged_chars);
> >  }
> >  
> 

Simon,

What's your opinion about this patch? It is a rh internal report.
Current code make sense, adding the patch will be slight better though
for kdump case. But if you do not like it we can ignore it and close
the bug.

Thanks
Dave