On 7/29/20 7:48 PM, Andrii Nakryiko wrote:
On Wed, Jul 29, 2020 at 7:29 AM Jakub Sitnicki jakub@cloudflare.com wrote:
On Wed, Jul 29, 2020 at 06:09 AM CEST, Andrii Nakryiko wrote:
Add test validating that all inner maps are released properly after skeleton is destroyed. To ensure determinism, trigger kernel-side synchronize_rcu() before checking map existence by their IDs.
Acked-by: Song Liu songliubraving@fb.com Signed-off-by: Andrii Nakryiko andriin@fb.com
[...]
+/*
- Trigger synchronize_cpu() in kernel.
Nit: synchronize_*r*cu().
welp, yeah
- ARRAY_OF_MAPS/HASH_OF_MAPS lookup/update operations trigger
- synchronize_rcu(), if looking up/updating non-NULL element. Use this fact
- to trigger synchronize_cpu(): create map-in-map, create a trivial ARRAY
- map, update map-in-map with ARRAY inner map. Then cleanup. At the end, at
- least one synchronize_rcu() would be called.
- */
That's a cool trick. I'm a bit confused by "looking up/updating non-NULL element". It looks like you're updating an element that is NULL/unset in the code below. What am I missing?
I was basically trying to say that it has to be a successful lookup or update. For lookup that means looking up non-NULL (existing) entry. For update -- setting valid inner map FD.
Not sure fixing this and typo above is worth it to post v5.
Nope, I'll fix it up while applying.