Messages in this thread | | | Subject | Re: [RFC PATCH bpf-next v2 4/4] error-injection: Support fault injection framework | From | Alexei Starovoitov <> | Date | Wed, 27 Dec 2017 14:49:46 -0800 |
| |
On 12/27/17 12:09 AM, Masami Hiramatsu wrote: > On Tue, 26 Dec 2017 18:12:56 -0800 > Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote: > >> On Tue, Dec 26, 2017 at 04:48:25PM +0900, Masami Hiramatsu wrote: >>> Support in-kernel fault-injection framework via debugfs. >>> This allows you to inject a conditional error to specified >>> function using debugfs interfaces. >>> >>> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> >>> --- >>> Documentation/fault-injection/fault-injection.txt | 5 + >>> kernel/Makefile | 1 >>> kernel/fail_function.c | 169 +++++++++++++++++++++ >>> lib/Kconfig.debug | 10 + >>> 4 files changed, 185 insertions(+) >>> create mode 100644 kernel/fail_function.c >>> >>> diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt >>> index 918972babcd8..6243a588dd71 100644 >>> --- a/Documentation/fault-injection/fault-injection.txt >>> +++ b/Documentation/fault-injection/fault-injection.txt >>> @@ -30,6 +30,11 @@ o fail_mmc_request >>> injects MMC data errors on devices permitted by setting >>> debugfs entries under /sys/kernel/debug/mmc0/fail_mmc_request >>> >>> +o fail_function >>> + >>> + injects error return on specific functions by setting debugfs entries >>> + under /sys/kernel/debug/fail_function. No boot option supported. >> >> I like it. >> Could you document it a bit better? > > Yes, I will do in next series. > >> In particular retval is configurable, but without an example no one >> will be able to figure out how to use it. > > Ah, right. BTW, as I pointed in the covermail, should we store the > expected error value range into the injectable list? e.g. > > ALLOW_ERROR_INJECTION(open_ctree, -1, -MAX_ERRNO) > > And provide APIs to check/get it.
I'm afraid such check would be too costly. Right now we have only two functions marked but I expect hundreds more will be added in the near future as soon as developers realize the potential of such error injection. All of ALLOW_ERROR_INJECTION marks add 8 byte overhead each to .data. Multiple by 1k and we have 8k of data spent on marks. If we add max/min range marks that doubles it for very little use. I think marking function only is enough.
| |