From: lpechacek@suse.com (Libor Pechacek)
Subject: [PATCH v3] selftests/livepatch: introduce tests
Date: Tue, 24 Apr 2018 19:19:02 +0200 [thread overview]
Message-ID: <20180424171902.z4ymubblh2dtcp4h@fmn.suse.cz> (raw)
Message-ID: <20180424171902.N1JCURdJOTG5T5uTJz7twpkmc_U_n3Hqd8TiYYnj_XU@z> (raw)
In-Reply-To: <c3f1a6b8-5eba-84e1-9d0b-8009c9087022@redhat.com>
On Tue 24-04-18 11:50:28, Joe Lawrence wrote:
> On 04/23/2018 10:43 AM, Joe Lawrence wrote:
> > On Fri, Apr 20, 2018@02:56:05PM +0200, Libor Pechacek wrote:
> >> On Thu 12-04-18 10:54:31, Joe Lawrence wrote:
> >>> + fi
> >>> + echo "$ret" > /dev/kmsg
> >>> +}
> >>> +
> >>> +# unload_mod(modname) - unload a kernel module
> >>> +# modname - module name to unload
> >>> +function unload_mod() {
> >>> + local mod="$1"
> >>> +
> >>> + # Wait for module reference count to clear ...
> >>> + local i=0
> >>> + while [[ $(cat /sys/module/"$mod"/refcnt) != "0" ]]; do
> >>> + i=$((i+1))
> >>> + if [[ $i -eq $MAX_RETRIES ]]; then
> >>> + die "failed to unload module $mod (refcnt)"
> >>> + fi
> >>> + sleep $RETRY_INTERVAL
> >>> + done
> >>
> >> The repeating pattern of "while <some test>; do <count>; if <count beyond max
> >> retries>; then <die>..." seems to ask for encapsulation.
> >>
> >
> > Yeah I definitely agree. I think at some point I had acquired
> > bash-fatigue; I wasn't sure how to cleanly wrap <some test> around that
> > extra logic. In C, I could do something clever with macros or a
> > callback function. My bash scripting isn't great, so I copied and
> > pasted my way through it. Suggestions welcome.
> >
>
> Okay, here's what I came up with... first off, do you prefer this kind
> of transition check vs. looking only at a specific module?
>
> # check_transition() - verify that no livepatch transition in effect
> function check_transition() {
> grep -q '^1$' /sys/kernel/livepatch/*/transition 2>/dev/null
> }
Elegant!
> then wrap the retry/timeout logic like:
>
> # retry_cmd(cmd) - loop a command until it is successful or
> # $MAX_RETRIES, sleeping $RETRY_INTERVAL in
> # between tries
> # cmd - command and its arguments to run
> function retry_cmd() {
> local cmd="$*"
> local i=0
> while eval "$cmd"; do
> i=$((i+1))
> [[ $i -eq $MAX_RETRIES ]] && return 1
> sleep $RETRY_INTERVAL
> done
> return 0
> }
>
> and the callers to something like:
>
> # wait_for_transition() - wait until all livepatch transitions clear
> function wait_for_transition() {
> retry_cmd check_transition ||
> die "failed to complete transition"
> }
My idea was to make the die() part of the retry loop. This implementation is,
however, more flexible.
> I can create similar check() functions to eval for sysfs file existence,
> file content, reference count, etc. to remove all the other
> retry/timeout loops.
I think check_*() functions can be avoided for trivial tests. retry_cmd() can
be passed a more complex command string than a single function name.
Regarding naming, I'd say wait_false() or similar would better describe what
retry_cmd() does.
Libor
--
Libor Pechacek
SUSE Labs
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next prev parent reply other threads:[~2018-04-24 17:19 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-12 14:54 [PATCH v3] Add livepatch kselftests joe.lawrence
2018-04-12 14:54 ` Joe Lawrence
2018-04-12 14:54 ` [PATCH v3] selftests/livepatch: introduce tests joe.lawrence
2018-04-12 14:54 ` Joe Lawrence
2018-04-12 21:36 ` jpoimboe
2018-04-12 21:36 ` Josh Poimboeuf
2018-04-13 11:20 ` mbenes
2018-04-13 11:20 ` Miroslav Benes
2018-04-13 20:52 ` joe.lawrence
2018-04-13 20:52 ` Joe Lawrence
2018-04-16 11:33 ` mbenes
2018-04-16 11:33 ` Miroslav Benes
2018-04-16 15:02 ` pmladek
2018-04-16 15:02 ` Petr Mladek
2018-04-17 8:06 ` mbenes
2018-04-17 8:06 ` Miroslav Benes
2018-04-17 13:25 ` joe.lawrence
2018-04-17 13:25 ` Joe Lawrence
2018-04-16 12:49 ` pmladek
2018-04-16 12:49 ` Petr Mladek
2018-04-20 12:56 ` lpechacek
2018-04-20 12:56 ` Libor Pechacek
2018-04-23 14:43 ` joe.lawrence
2018-04-23 14:43 ` Joe Lawrence
2018-04-24 15:50 ` joe.lawrence
2018-04-24 15:50 ` Joe Lawrence
2018-04-24 17:19 ` lpechacek [this message]
2018-04-24 17:19 ` Libor Pechacek
2018-04-24 17:35 ` lpechacek
2018-04-24 17:35 ` Libor Pechacek
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