On Tue, 2020-03-24 at 16:03 -0500, Benjamin Marzinski wrote: > If dm_hold_control_open() isn't set, when dm_lib_release() is called, > it > will close the control fd. The control fd will get re-opened on the > next > dm_task_run() call, but if there is a dm_task_run() call already > in progress in another thread, it can fail. Since many of the > device-mapper callouts happen with the vecs lock held, this wasn't > too > noticeable, but there is code that calls dm_task_run() without the > vecs lock held, notably the dmevent waiter code. > > Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx> > --- > libmultipath/devmapper.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c > index bed8ddc6..d96472fe 100644 > --- a/libmultipath/devmapper.c > +++ b/libmultipath/devmapper.c > @@ -254,6 +254,7 @@ void libmp_dm_init(void) > memcpy(conf->version, version, sizeof(version)); > put_multipath_config(conf); > dm_init(verbosity); > + dm_hold_control_dev(1); > dm_udev_set_sync_support(libmp_dm_udev_sync); > } AFAICS, this function has been in libdm since 1.02.111. We support 1.02.89 (if all features enabled, otherwise even older). Perhaps we should make this function call conditional on the libdm verson? But perhaps more importantly, why do we still need to call dm_lib_release()? AFAICS it's only needed for systems that have no udev support for creating device nodes (to call update_devs() via dm_lib_release()), and we don't support that anymore anyway, do we? Since 26c4bb0, we're always setting the DM_UDEV_DISABLE_LIBRARY_FALLBACK flag, and the cookie, too (we aren't setting it for DM_DEVICE_RELOAD, but it isn't needed for that, either, since no device nodes need to be created or removed); so dm_lib_release() should really have no effect. Regards Martin -- Dr. Martin Wilck <mwilck@xxxxxxxx>, Tel. +49 (0)911 74053 2107 SUSE Software Solutions Germany GmbH HRB 36809, AG Nürnberg GF: Felix Imendörffer -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
