4.7-stable review patch. If anyone has any objections, please let me know.
------------------ From: Alexander Usyskin <alexander.usys...@intel.com> commit e728ae271f4cf71218ec06a6daf61b79466cb466 upstream. The device lock was unnecessary obtained in bus rescan work before the amthif client search. That causes incorrect lock ordering and task hang: ... [88004.613213] INFO: task kworker/1:14:21832 blocked for more than 120 seconds. ... [88004.645934] Workqueue: events mei_cl_bus_rescan_work ... The correct lock order is cl_bus_lock device_lock me_clients_rwsem Move device_lock into amthif init function that called after me_clients_rwsem is released. This fixes regression introduced by commit: commit 025fb792bac3 ("mei: split amthif client init from end of clients enumeration") Signed-off-by: Alexander Usyskin <alexander.usys...@intel.com> Signed-off-by: Tomas Winkler <tomas.wink...@intel.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/misc/mei/amthif.c | 12 +++++++++--- drivers/misc/mei/bus.c | 2 -- 2 files changed, 9 insertions(+), 5 deletions(-) --- a/drivers/misc/mei/amthif.c +++ b/drivers/misc/mei/amthif.c @@ -67,8 +67,12 @@ int mei_amthif_host_init(struct mei_devi struct mei_cl *cl = &dev->iamthif_cl; int ret; - if (mei_cl_is_connected(cl)) - return 0; + mutex_lock(&dev->device_lock); + + if (mei_cl_is_connected(cl)) { + ret = 0; + goto out; + } dev->iamthif_state = MEI_IAMTHIF_IDLE; @@ -77,11 +81,13 @@ int mei_amthif_host_init(struct mei_devi ret = mei_cl_link(cl); if (ret < 0) { dev_err(dev->dev, "amthif: failed cl_link %d\n", ret); - return ret; + goto out; } ret = mei_cl_connect(cl, me_cl, NULL); +out: + mutex_unlock(&dev->device_lock); return ret; } --- a/drivers/misc/mei/bus.c +++ b/drivers/misc/mei/bus.c @@ -983,12 +983,10 @@ void mei_cl_bus_rescan_work(struct work_ container_of(work, struct mei_device, bus_rescan_work); struct mei_me_client *me_cl; - mutex_lock(&bus->device_lock); me_cl = mei_me_cl_by_uuid(bus, &mei_amthif_guid); if (me_cl) mei_amthif_host_init(bus, me_cl); mei_me_cl_put(me_cl); - mutex_unlock(&bus->device_lock); mei_cl_bus_rescan(bus); }