On Wed, Mar 25, 2020 at 03:16:50PM +0000, Martin Wilck wrote: > 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 Good call. I'll redo this patch. -Ben > > -- > 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
