Re: [PATCH 0/2][v2] Add the ability to do BPF directed error injection

[Alexei Starovoitov]

On 10/31/17 6:55 PM, David Miller wrote:
> From: Josef Bacik <josef@xxxxxxxxxxxxxx>
> Date: Tue, 31 Oct 2017 11:45:55 -0400
>
> > v1->v2:
> > - moved things around to make sure that bpf_override_return could really only be
> >   used for an ftrace kprobe.
> > - killed the special return values from trace_call_bpf.
> > - renamed pc_modified to bpf_kprobe_state so bpf_override_return could tell if
> >   it was being called from an ftrace kprobe context.
> > - reworked the logic in kprobe_perf_func to take advantage of bpf_kprobe_state.
> > - updated the test as per Alexei's review.
> >
> > A lot of our error paths are not well tested because we have no good way of
> > injecting errors generically.  Some subystems (block, memory) have ways to
> > inject errors, but they are random so it's hard to get reproduceable results.
> >
> > With BPF we can add determinism to our error injection.  We can use kprobes and
> > other things to verify we are injecting errors at the exact case we are trying
> > to test.  This patch gives us the tool to actual do the error injection part.
> > It is very simple, we just set the return value of the pt_regs we're given to
> > whatever we provide, and then override the PC with a dummy function that simply
> > returns.
> >
> > Right now this only works on x86, but it would be simple enough to expand to
> > other architectures.  Thanks,
>
> This appears to moreso target the tracing tree than the networking tree.
>
> Let me know if that's not the case and I should be the one intergrating
> these changes.

i don't think it will apply to anything but net-next. If it goes any
other tree we will have major conflicts during merge window.
btw I haven't reviewed them for the second time.