On Thu, May 13, 2021 at 09:53:58PM +0200, mwilck@xxxxxxxx wrote: > From: Martin Wilck <mwilck@xxxxxxxx> > > To avoid race conditions with pending RCU callbacks on exit, it's > necessary to call rcu_barrier() in cleanup_rcu() (see > https://lists.lttng.org/pipermail/lttng-dev/2021-May/029958.html and > follow-ups). > > rcu_barrier() is only available in User-space RCU v0.8 and newer. > Fix it by reverting 5d0dae6 ("multipathd: Fix liburcu memory leak") > if an older version of liburcu is detected. > > Fixes: 5d0dae6 ("multipathd: Fix liburcu memory leak") > Signed-off-by: Martin Wilck <mwilck@xxxxxxxx> Reviewed-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx> > > --- > v2: Use $(PKGCONFIG) (Ben Marzinski); remove "\n" in awk. > > --- > multipathd/Makefile | 2 ++ > multipathd/main.c | 17 +++++++++++++++-- > 2 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/multipathd/Makefile b/multipathd/Makefile > index d053c1e..393b6cb 100644 > --- a/multipathd/Makefile > +++ b/multipathd/Makefile > @@ -16,6 +16,8 @@ LDFLAGS += $(BIN_LDFLAGS) > LIBDEPS += -L$(multipathdir) -lmultipath -L$(mpathpersistdir) -lmpathpersist \ > -L$(mpathcmddir) -lmpathcmd -ludev -ldl -lurcu -lpthread \ > -ldevmapper -lreadline > +CFLAGS += $(shell $(PKGCONFIG) --modversion liburcu 2>/dev/null | \ > + awk -F. '{ printf("-DURCU_VERSION=0x%06x", 256 * ( 256 * $$1 + $$2) + $$3); }') > > ifdef SYSTEMD > CFLAGS += -DUSE_SYSTEMD=$(SYSTEMD) > diff --git a/multipathd/main.c b/multipathd/main.c > index 102946b..c34fd9c 100644 > --- a/multipathd/main.c > +++ b/multipathd/main.c > @@ -3031,6 +3031,10 @@ static void cleanup_threads(void) > pthread_attr_destroy(&waiter_attr); > } > > +#ifndef URCU_VERSION > +# define URCU_VERSION 0 > +#endif > +#if (URCU_VERSION >= 0x000800) > /* > * Use a non-default call_rcu_data for child(). > * > @@ -3040,6 +3044,9 @@ static void cleanup_threads(void) > * can't be joined with pthread_join(), leaving a memory leak. > * > * Therefore we create our own, which can be destroyed and joined. > + * The cleanup handler needs to call rcu_barrier(), which is only > + * available in user-space RCU v0.8 and newer. See > + * https://lists.lttng.org/pipermail/lttng-dev/2021-May/029958.html > */ > static struct call_rcu_data *setup_rcu(void) > { > @@ -3072,6 +3079,7 @@ static void cleanup_rcu(void) > } > rcu_unregister_thread(); > } > +#endif /* URCU_VERSION */ > > static void cleanup_child(void) > { > @@ -3116,9 +3124,14 @@ child (__attribute__((unused)) void *param) > init_unwinder(); > mlockall(MCL_CURRENT | MCL_FUTURE); > signal_init(); > +#if (URCU_VERSION >= 0x000800) > mp_rcu_data = setup_rcu(); > - > - if (atexit(cleanup_rcu) || atexit(cleanup_child)) > + if (atexit(cleanup_rcu)) > + fprintf(stderr, "failed to register RCU cleanup handler\n"); > +#else > + rcu_init(); > +#endif > + if (atexit(cleanup_child)) > fprintf(stderr, "failed to register cleanup handlers\n"); > > setup_thread_attr(&misc_attr, 64 * 1024, 0); > -- > 2.31.1 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
