Figured out what rcu_read_ongoing does. It just returns true if it's called within a read section and false otherwise. The problem for catching whether reads are done outside read sections is that you can not make macros for read and write operations. e.g. ptr->a = 4;.
tir. 2. sep. 2025 kl. 16:17 skrev Thobias Knudsen <thob...@gmail.com>: > > I suspect that what you are trying to achieve is validation that > > calls to functions that require to be within a RCU read-side critical > > section such as cds_lfht_lookup are indeed invoked from within a > > critical section. > > Yes exactly, but not only for read sections. It could also be to validate > that rcu_barrier isnt called within a callback function or that > rcu_quiescent_state isnt called when thread is offline > > > We've added a "rcu_read_ongoing()" API for that purpose to liburcu > > RCU flavors, but AFAIK it's not used for any kind of validation > > within cds_lfht. This could indeed become a feature request that > > would apply to all liburcu data structure APIs. > > I can't find any documentation on rcu_read_ongoing. Btw the documentation > for urcu in general is scattered all around the repo it seems. It should > have been all at one place imo. Should I make a feature request for it? I > don't know how stuff works inside this repo though. > > > > man. 1. sep. 2025 kl. 17:09 skrev Mathieu Desnoyers < > mathieu.desnoy...@efficios.com>: > >> On 2025-08-31 16:48, Thobias Knudsen wrote: >> > BTW i've made a macro library which overrides the >> > urcu and lfht functions. It checks that you call the functions in the >> > correct order. This has been really useful for debugging and I think it >> > would be useful to have it integrated into urcu to make the it more >> user >> > friendly. you could have it integrated with the macro DEBUG_RCU or make >> > a new one, maybe DEBUG_FUNCTION_CALL_ORDER. The only thing it doesn't >> > catch is if you continue to use data from cds_lfht_lookup() after >> > rcu_read_unlock() >> >> I suspect that what you are trying to achieve is validation that >> calls to functions that require to be within a RCU read-side critical >> section such as cds_lfht_lookup are indeed invoked from within a >> critical section. >> >> We've added a "rcu_read_ongoing()" API for that purpose to liburcu >> RCU flavors, but AFAIK it's not used for any kind of validation >> within cds_lfht. This could indeed become a feature request that >> would apply to all liburcu data structure APIs. >> >> Thanks, >> >> Mathieu >> >> > >> > søn. 31. aug. 2025 kl. 22:42 skrev Thobias Knudsen <thob...@gmail.com >> > <mailto:thob...@gmail.com>>: >> > >> > First question: why isn't Userspace RCU more popular? >> > Second question: Why isn't it possible to create issues in the urcu >> > repo? Im asking for a feature here: >> > Is it possible to make a function which checks if there are more >> > callbacks queued by call_rcu? I need that because there are some >> > callbacks which call call_rcu, and then calling rcu_barrier once >> > isn't enough and I therefore need a way to check if there are still >> > callbacks to wait on before terminating the program. No worries if >> > this is too much to ask for or if it isn't possible. This >> > functionality is only needed in termination because otherwise >> > isn't needed to call rcu_barrier multiple times (at least so far) >> > >> > Best regards >> > Thobias >> > >> > >> >> >> -- >> Mathieu Desnoyers >> EfficiOS Inc. >> https://www.efficios.com >> >
