On Fri, Dec 04, 2020 at 06:42:56PM +0100, Sebastian Andrzej Siewior wrote: > iser_initialize_task_headers() uses in_interrupt() to find out if it is > safe to acquire a mutex. > > in_interrupt() is deprecated as it is ill defined and does not provide what > it suggests. Aside of that it covers only parts of the contexts in which > a mutex may not be acquired. > > The following callchains exist: > > iscsi_queuecommand() *locks* iscsi_session::frwd_lock > -> iscsi_prep_scsi_cmd_pdu() > -> session->tt->init_task() (iscsi_iser_task_init()) > -> iser_initialize_task_headers() > -> iscsi_iser_task_xmit() (iscsi_transport::xmit_task) > -> iscsi_iser_task_xmit_unsol_data() > -> iser_send_data_out() > -> iser_initialize_task_headers() > > iscsi_data_xmit() *locks* iscsi_session::frwd_lock > -> iscsi_prep_mgmt_task() > -> session->tt->init_task() (iscsi_iser_task_init()) > -> iser_initialize_task_headers() > -> iscsi_prep_scsi_cmd_pdu() > -> session->tt->init_task() (iscsi_iser_task_init()) > -> iser_initialize_task_headers() > > __iscsi_conn_send_pdu() caller has iscsi_session::frwd_lock > -> iscsi_prep_mgmt_task() > -> session->tt->init_task() (iscsi_iser_task_init()) > -> iser_initialize_task_headers() > -> session->tt->xmit_task() ( > > The only callchain that is close to be invoked in preemptible context: > iscsi_xmitworker() worker > -> iscsi_data_xmit() > -> iscsi_xmit_task() > -> conn->session->tt->xmit_task() (iscsi_iser_task_xmit() > > In iscsi_iser_task_xmit() there is this check: > if (!task->sc) > return iscsi_iser_mtask_xmit(conn, task); > > so it does end up in iser_initialize_task_headers() and > iser_initialize_task_headers() relies on iscsi_task::sc == NULL. > > Remove conditional locking of iser_conn::state_mutex because there is no > call chain to do so. Remove the goto label and return early now that > there is no clean up needed. > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > Cc: Sagi Grimberg <sagi@xxxxxxxxxxx> > Cc: Max Gurtovoy <maxg@xxxxxxxxxx> > Cc: Doug Ledford <dledford@xxxxxxxxxx> > Cc: Jason Gunthorpe <jgg@xxxxxxxx> > Cc: linux-rdma@xxxxxxxxxxxxxxx > --- Applied to for-next, thanks Jason
