On Wed, Mar 20, 2024 at 6:49 AM Zijie Zhao <zzjas98@xxxxxxxxx> wrote: > > Dear IPVS maintainers, > > We encountered an unusual usage of sysctl parameter while analyzing > kernel source code. > > > In include/net/ip_vs.h, line 1062 - 1070: > > ``` > static inline int sysctl_sync_threshold(struct netns_ipvs *ipvs) > { > return ipvs->sysctl_sync_threshold[0]; > } > > static inline int sysctl_sync_period(struct netns_ipvs *ipvs) > { > return READ_ONCE(ipvs->sysctl_sync_threshold[1]); > } > ``` > > Here, sysctl_sync_threshold[1] is accessed behind `READ_ONCE`, but > sysctl_sync_threshold[0] is not. Should sysctl_sync_threshold[0] also be > guarded by `READ_ONCE`? I'm not so sure and clear about the detailed history. AFAIK, readers accessing this sysctl knob (sysctl_sync_threshold) should be protected by READ_ONCE() because it can be changed concurrently. Probably the commit 749c42b620a95 missed this point many years ago and then commit 6aa7de059173a followed that. Thanks, Jason > > Please kindly let us know if we missed any key information and this is > actually intended. We appreciate your information and time! Thanks! > > > Links to the code: > https://elixir.bootlin.com/linux/v6.8.1/source/include/net/ip_vs.h#L1064 > https://elixir.bootlin.com/linux/v6.8.1/source/include/net/ip_vs.h#L1069 > > Best, > Zijie >