Matias Elo(matiaselo) replied on github web page: platform/linux-generic/pktio/netmap.c line 14 @@ -388,13 +389,22 @@ static int netmap_open(odp_pktio_t id ODP_UNUSED, pktio_entry_t *pktio_entry, if (pkt_nm->is_virtual) { static unsigned mac; + uint32_t tid = syscall(SYS_gettid); + + if ((int)tid == -1)
Comment: syscall() specification still defines -1 as an error return value and we should adhere to the spec regardless of the function implementation which may change. > muvarov wrote > . >> muvarov wrote >> man gettid says that it always passes. >> >> kernel code is also: >> pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, >> struct pid_namespace *ns) >> { >> pid_t nr = 0; >> >> rcu_read_lock(); >> if (!ns) >> ns = task_active_pid_ns(current); >> if (likely(pid_alive(task))) { >> if (type != PIDTYPE_PID) >> task = task->group_leader; >> nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns); >> } >> rcu_read_unlock(); >> >> return nr; >> } >> EXPORT_SYMBOL(__task_pid_nr_ns); >> >> I.e. it will return init process tid 0 in worst case. So this check is not >> correct and not needed. >> >> It might be needed additional cast: >> uint32_t tid = (uint32_t)syscall(SYS_gettid) because of syscall returns >> pid_t. >>> muvarov wrote >>> @lumag we also use SYS_gettid() in shm and timer. I think that is not >>> subject for this PR. Just general clean up. >>>> Bill Fischofer(Bill-Fischofer-Linaro) wrote: >>>> See >>>> [here](https://stackoverflow.com/questions/21279649/getting-error-in-c-program-undefined-reference-to-gettid) >>>> for an interesting discussion of why gettid() is not used. >>>>> Dmitry Eremin-Solenikov(lumag) wrote: >>>>> @matiaselo @muvarov Hmm. I thought that there is already a Glibc wrapper. >>>>> I would prefer this as a separate function, but it is of minor priority >>>>> then. >>>>>> muvarov wrote >>>>>> it was copied from netmap source I think. gittid() will generate >>>>>> warning due to missing glibc wrapper: >>>>>> https://stackoverflow.com/questions/30680550/c-gettid-was-not-declared-in-this-scope >>>>>> Maybe something already changed... >>>>>>> Matias Elo(matiaselo) wrote: >>>>>>> What's the benefit from using gettid()? It seems like the only >>>>>>> difference is that gettid() cannot fail. >>>>>>>> Dmitry Eremin-Solenikov(lumag) wrote: >>>>>>>> Why don't you use `gettid()` function? Then you can check for its >>>>>>>> existence in `configure.ac` and provide replacement implementation. https://github.com/Linaro/odp/pull/237#discussion_r146774223 updated_at 2017-10-25 07:32:34