On Mon, Mar 28, 2016 at 05:45:42PM +0800, Chung-Lin Tang wrote: > Hi Jakub, there's a path for deadlock on acc_device_lock when going > through the acc_set_device_type() OpenACC library function. > Basically, the gomp_init_targets_once() function should not be > called with that held. The attached patch moves it appropriately. > > Also in this patch, there are several cases in acc_* functions > where gomp_init_targets_once() is guarded by a test of > !cached_base_dev. Since that function already uses pthread_once() to > call gomp_target_init(), and technically cached_base_dev > is protected by acc_device_lock, the cleanest way should be to > simply drop those "if(!cached_base_dev)" tests. > > Tested libgomp without regressions on an nvptx offloaded system, > is this okay for trunk?
Ok, with ChangeLog nits: > > 2016-03-28 Chung-Lin Tang <clt...@codesourcery.com> > > * oacc-init.c (acc_init): Remove !cached_base_dev condition on call to > gomp_init_targets_once(). > (acc_set_device_type): Remove !cached_base_dev condition on call to > gomp_init_targets_once(), move call to before acc_device_lock acquire, > to avoid deadlock. > (acc_get_device_num): Remove !cached_base_dev condition on call to > gomp_init_targets_once(). > (acc_set_device_num): Likewise. Please just use gomp_init_targets_once instead of gomp_init_targets_once() in the ChangeLog. > Index: oacc-init.c > =================================================================== > --- oacc-init.c (revision 234502) > +++ oacc-init.c (working copy) > @@ -433,8 +433,7 @@ goacc_attach_host_thread_to_device (int ord) > void > acc_init (acc_device_t d) > { > - if (!cached_base_dev) > - gomp_init_targets_once (); > + gomp_init_targets_once (); > > gomp_mutex_lock (&acc_device_lock); > > @@ -498,11 +497,10 @@ acc_set_device_type (acc_device_t d) > struct gomp_device_descr *base_dev, *acc_dev; > struct goacc_thread *thr = goacc_thread (); > > + gomp_init_targets_once (); > + > gomp_mutex_lock (&acc_device_lock); > > - if (!cached_base_dev) > - gomp_init_targets_once (); > - > cached_base_dev = base_dev = resolve_device (d, true); > acc_dev = &base_dev[goacc_device_num]; > > @@ -563,8 +561,7 @@ acc_get_device_num (acc_device_t d) > if (d >= _ACC_device_hwm) > gomp_fatal ("unknown device type %u", (unsigned) d); > > - if (!cached_base_dev) > - gomp_init_targets_once (); > + gomp_init_targets_once (); > > gomp_mutex_lock (&acc_device_lock); > dev = resolve_device (d, true); > @@ -584,8 +581,7 @@ acc_set_device_num (int ord, acc_device_t d) > struct gomp_device_descr *base_dev, *acc_dev; > int num_devices; > > - if (!cached_base_dev) > - gomp_init_targets_once (); > + gomp_init_targets_once (); > > if (ord < 0) > ord = goacc_device_num; Jakub