Re: synchronize_rcu

[Roman Savchenko <gmstima at gmail dot com>]

Hi David,

Yes it seems to work. I'm not sure that this patch is generic purpose,
because the kernel is RTOS RedHawk and this changes is from JRCU
implementation (some discussion threads https://lwn.net/Articles/431885/,
http://lkml.iu.edu/hypermail/linux/kernel/1103.1/02281.html). And it does
not pass 'make check', but I am not sure that tests' failures go from rcu,
e.g.:

FAIL: stap -p4 -e { probe nfs.proc.read_done { println(server_ip) } }
FAIL: stap -p4 -e { probe nfs.proc.read_setup { println(count) } }

semantic error: invalid access '->task' vs 'void*': operator '->' at
/root/projects/systemtap/build/share/systemtap/tapset/linux/nfs_proc.stpm:16:21
        source:     ( get_ip(&@nfs_data->task) )
                                       ^

So should I send patch?

Regards,
Roman


2017-10-06 19:20 GMT+03:00 David Smith <dsmith@redhat.com>:

> That sounds reasonable. Does it seem to work? If so, please send us a
> patch and we'll include it.
>
> On Thu, Oct 5, 2017 at 11:08 AM, Roman Savchenko <gmstima@gmail.com>
> wrote:
> > Hi All,
> >
> > I'm using kernel based on some PREAMT_RT patches (4.1.15-rt17). This
> kernel
> > does not provide synchronize_rcu in Modules.symver, that triggers an
> error:
> > "No implementation for stp_synchronize_sched!". But it provides
> > rcu_synchronize_sched. I found in kernel code such define:
> >
> > ./include/linux/jrcu.h:#define synchronize_rcu
> > rcu_synchronize_sched
> >
> > So I did the same:
> >
> > output_exportconf(s, o, "rcu_synchronize_sched",
> > "STAPCONF_SYNCHRONIZE_RCU");
> >
> > Am I correct?
> >
> > Many thanks,
> > Roman Savchenko
>
>
>
> --
> David Smith
> Principal Software Engineer
> Red Hat
>