[igt-dev] [PATCH i-g-t v3] runner: Show kernel state on detecting test timeout

[Chris Wilson]

Quoting Petri Latvala (2019-10-14 07:58:35)
> On Fri, Oct 11, 2019 at 02:22:37PM +0100, Chris Wilson wrote:
> > When our watchdog expires and we declare the test has timed out, we send
> > it a signal to terminate. The test will produce a backtrace upon receipt
> > of that signal, but often times (especially as we do test and debug the
> > kernel), the test is hung inside the kernel. So we need the kernel state
> > to see where the live/deadlock is occuring. Enter sysrq-t to show the
> > backtraces of all processes (as the one we are searching for may be
> > sleeping).
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Petri Latvala <petri.latvala at intel.com>
> > ---
> >  runner/executor.c | 21 +++++++++++++++++++++
> >  1 file changed, 21 insertions(+)
> > 
> > diff --git a/runner/executor.c b/runner/executor.c
> > index 1a00237fc..2bb828278 100644
> > --- a/runner/executor.c
> > +++ b/runner/executor.c
> > @@ -638,6 +638,25 @@ static const char *get_cmdline(pid_t pid, char *buf, ssize_t len)
> >       return buf;
> >  }
> >  
> > +static bool sysrq(char cmd)
> > +{
> > +     bool success = false;
> > +     int fd;
> > +
> > +     fd = open("/proc/sysrq-trigger", O_WRONLY);
> > +     if (fd >= 0) {
> > +             success = write(fd, &cmd, 1) == 1;
> > +             close(fd);
> > +     }
> 
> 
> Where does the dump go? Are we able to grab it in the test's dmesg?

Into the dmesg.
-Chris