Re: [RFC PATCH bpf-next v2 0/4] Separate error injection table from kprobes

On Thu, 4 Jan 2018 11:07:16 -0500
Josef Bacik [off-list ref] wrote:

On Tue, Dec 26, 2017 at 04:46:28PM +0900, Masami Hiramatsu wrote:

quoted

Hi Josef and Alexei,

Here are the 2nd version of patches to moving error injection
table from kprobes. In this series I did a small fixes and
add function-based fault injection.

Here is the previous version:

https://lkml.org/lkml/2017/12/22/554

There are 2 main reasons why I separate it from kprobes.

 - kprobes users can modify execution path not only at 
   error-injection whitelist functions but also other
   functions. I don't like to suggest user that such
   limitation is from kprobes itself.

 - This error injection information is also useful for
   ftrace (function-hook) and livepatch. It should not
   be limited by CONFIG_KPROBES.

So I introduced CONFIG_FUNCTION_ERROR_INJECTION for this feature.
Also CONFIG_FAIL_FUNCTION is added, which provides function-based
error injection interface via debugfs following fault-injection
framework. See [4/4].

Any thoughts?

Sorry Masami, I've been on vacation for the last two weeks.  This approach is
fine by me, if we want to allow other mechanisms other than bpf to use this
functionality then hooray.  I'll do a proper review when you post v3, just
wanted to let you know I wasn't ignoring you.  Thanks,

Yeah, thank you for the kindful notice ;)

BTW, could you tell me how I can run your test case?

When I tried to build the tests (samples/bpf) I got below error and stopped.

[mhiramat@devbox bpf]$ LANG=C make 
make -C ../../ /home/mhiramat/ksrc/linux/samples/bpf/
make[1]: Entering directory '/home/mhiramat/ksrc/linux'
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/bounds.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/asm-offsets.h
  CALL    scripts/checksyscalls.sh
  DESCEND  objtool
  CHK     scripts/mod/devicetable-offsets.h
  HOSTCC  /home/mhiramat/ksrc/linux/samples/bpf/test_lru_dist.o
/home/mhiramat/ksrc/linux/samples/bpf/test_lru_dist.c:39:8: error: redefinition of 'struct list_head'
 struct list_head {
        ^~~~~~~~~
In file included from /home/mhiramat/ksrc/linux/samples/bpf/test_lru_dist.c:9:0:
./tools/include/linux/types.h:69:8: note: originally defined here
 struct list_head {
        ^~~~~~~~~
make[2]: *** [scripts/Makefile.host:107: /home/mhiramat/ksrc/linux/samples/bpf/test_lru_dist.o] Error 1
make[1]: *** [Makefile:1675: /home/mhiramat/ksrc/linux/samples/bpf/] Error 2
make[1]: Leaving directory '/home/mhiramat/ksrc/linux'
make: *** [Makefile:204: all] Error 2


Thank you,

-- 
Masami Hiramatsu [off-list ref]