2016-08-04 0:05 GMT+09:00 Vegard Nossum <vegard.nos...@oracle.com>: > Before this patch, fault injection uses a combination of randomness and > frequency to determine where to inject faults. The problem with this is > that code paths which are executed very rarely get proportional amounts > of faults injected. > > A better heuristic is to look at the actual callchain leading up to the > possible failure point; if we see a callchain that we've never seen up > until this point, chances are it's a rare one and we should definitely > inject a fault here (since we might not get the chance again later). > > This uses a probabilistic set structure (similar to a bloom filter) to > determine whether we have seen a particular callchain before by hashing > the stack trace and atomically testing/setting a bit corresponding to > the current callchain. > > There is a possibility of false negatives (i.e. we think we have seen a > particular callchain before when in fact we haven't, therefore we don't > inject a fault where we should have). We might use some sort of random > seed here, but the additional complexity doesn't seem worth it to me. > > This finds a lot more bugs than just plain fault injection. > > Signed-off-by: Vegard Nossum <vegard.nos...@oracle.com> > --- > lib/Kconfig.debug | 29 +++++++++++++++++++++++++++++ > lib/fault-inject.c | 36 +++++++++++++++++++++++++++++++----- > 2 files changed, 60 insertions(+), 5 deletions(-) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 52f7e14..9e81720 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1701,6 +1701,35 @@ config FAULT_INJECTION_STACKTRACE_FILTER > help > Provide stacktrace filter for fault-injection capabilities > > +config FAULT_INJECTION_AT_NEW_CALLSITES > + bool "Inject fault the first time at a new callsite"
Isn't it better to make a run time configurable option instead of the build option?
