Am Fri, 9 Feb 2018 18:23:47 +0100 schrieb "[ext] Henning Schild" <henning.sch...@siemens.com>:
> Am Fri, 9 Feb 2018 17:48:22 +0100 > schrieb Jan Kiszka <jan.kis...@siemens.com>: > > > On 2018-02-09 17:13, Henning Schild wrote: > > > When using dlopen() to include xenomai libraries into an > > > application, __xenomai_init could be running in multiple threads > > > at a time. That happens if the application dlopens multiple libs > > > in multiple threads. > > > > So, dlopen itself is thread-safe, but it does not guarantee > > atomicity for the init functions it executes? Or would we run > > xenomai_init_dso manually in that case? > > According to its man-page dlopen is MT-Safe, but i do not think that > necessarily means it will serialize the init functions for us. I think > i will have to read the code to answer this one. I just had a look at glibc, and it looks like dlopen contains a big dlopen-lock as well. https://sourceware.org/git/?p=glibc.git;a=blob;f=elf/dl-open.c;h=0e37dd74b603ba07f677f2b4cf21661de5379529;hb=23158b08a0908f381459f273a984c6fd328363cb#l541 dl_open_worker will be called only under that lock and that is where a function named _dl_init gets called. uclibc also uses a big lock around all dlopen activity. It all looks like my patch is not required. Henning > Henning > > > > > > > Introduce a big lock to serialize all calls to __xenomai_init. > > > > > > Signed-off-by: Henning Schild <henning.sch...@siemens.com> > > > --- > > > lib/boilerplate/setup.c | 5 +++++ > > > 1 file changed, 5 insertions(+) > > > > > > diff --git a/lib/boilerplate/setup.c b/lib/boilerplate/setup.c > > > index f749828b91..653bbae104 100644 > > > --- a/lib/boilerplate/setup.c > > > +++ b/lib/boilerplate/setup.c > > > @@ -55,6 +55,9 @@ static int main_init_done; > > > > > > static DEFINE_PRIVATE_LIST(setup_list); > > > > > > +// serialize dlopen() init calls, which come potentially > > > multi-threaded > > > > Style: we use /* */ comments. > > > > > +static pthread_mutex_t dso_init_lock = PTHREAD_MUTEX_INITIALIZER; > > > + > > > static const struct option base_options[] = { > > > { > > > #define help_opt 0 > > > @@ -657,7 +660,9 @@ void xenomai_init(int *argcp, char *const > > > **argvp) > > > void xenomai_init_dso(int *argcp, char *const **argvp) > > > { > > > + write_lock_nocancel(&dso_init_lock); > > > __xenomai_init(argcp, argvp, "DSO"); > > > + write_unlock(&dso_init_lock); > > > trace_me("DSO bootstrap done"); > > > } > > > > > > > > > > Jan > > > _______________________________________________ > Xenomai mailing list > Xenomai@xenomai.org > https://xenomai.org/mailman/listinfo/xenomai _______________________________________________ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai
