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

Subrata Modak
2010-10-13T06:56:22Z

On Wed, 2010-10-13 at 12:22 +0530, Subrata Modak wrote:
> On Wed, 2010-10-13 at 13:30 +0800, hake huang wrote:
> > 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?
>
> I believe the functionality your original patch was proposing is already
> in LTP . I guess they will solve your problem. See the following
> commits:
>
> git show e3bc3758d3e4d17a0e04009ef873df53819b9ec6
> git show bd9d440be1da8020c93ac92e497e3a16e66e9fa3
>
> Just use:
>
> ./runltp -K <DMESG_DIRECTORY_NAME>

Basically, its a choice given to users who would like to record the
kernel messages, and not forcing recording all kernel messages which
your original patch is proposing :-)

Regards--
Subrata

>
> option while running ltp.
>
> Regards--
> Subrata
>
> > >
> > > > 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
>
>
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