Re: [LTP] Patch to record kernel dump message to each testcases log

hake huang
2010-10-13T05:30:13Z

2010/10/13 Garrett Cooper <yanegomi@gmail.com>
>
> On Tue, Oct 12, 2010 at 9:38 PM, hake huang <hakehuang@gmail.com> wrote:
> > Hi
> >
> > I see this simple solution is no quite fit. But the kernel dump message for
> > each test case is necessary for analysing. I can work on this further, with
> > below help:
> > 1. Where can I find the reason for the IIRC break?
>
> IIRC -> If I remember correctly.
so I need ask Subrata about this problem, right? what is the existing
functionality?
>
> > 2. Can it  be an option to avoid the size limitation on some embedded
> > system?
>
> No. This is outside the realm of LTP, but we must remain conscious of
> the fact that there are folks running LTP on cellphones, etc, where
> space is very much a luxury.
I see. but why can't they run in quit_mode?
>
> > 3.  A kind of seperating tag is needed for kernel message, right? e.g
> > <kernel_dump_start>dump message<kernel_dump_end>
>
> I think that adding an optional capture feature might be worthwhile,
> but you'll no doubt quickly find with some processes that the dmesg
> buffer will fill up quickly.
I have seen such events, and such cases need to be checked manually.
>
> > 4.  I see in ltp-pan.c the file descriptors, terminals are changed in child
> > process. if the system(3) has problem, the worst cases is there are no
> > kernel messge output in parent process, but the pan can still function well.
>
> Can you say that with 100% certainty? One of the potential problems
> with system is the fact that it allocates a shell and depending on how
> processes are executed and how file descriptors are cleaned up,
>
> Actually, pan makes zero attempts at closing open file descriptors and
> the like, so the problem is still very much with pan.
>
So your concerns is about file descriptors which open in ltp process,
I think this is an existing problem. I mean maybe pan need to attempt
to close open file descriptors. system(3) only increases the change of
occurrence caused by this problem, right?
> > if not use system(3), can you give your suggestion on this, exec(3) seems to
> > have the same problem as system(3)?
>
> Yes and no. In this case the problems that exist with open file
> descriptor inheritance, etc are unfortunately no worse from that
> perspective than your proposed code would do, but there are still
> other problems that need to be resolved with your proposed change
> anyhow that are much more pressing.
>
> -Garrett