Both the TX (iscsi_queuecommand, iscsi_xmit_task, iscsi_conn_send_pdu) and the RX (iscsi_complete_pdu and iser/tcp as well) code flows compete on the session lock. Since the RX flow runs in softirq/bh/tasklet context, if it cuts the TX flow on the same cpu, a deadlock may happen. To prevent that, make iscsi_queuecommand use the _bh form of spin lock/unlock in the same manner done by iscsi_xmit_task and iscsi_conn_send_pdu
Signed-off-by: Or Gerlitz <[email protected]> --- Mike, I am debugging some enhancement to iser and came a cross this. I really don't see why it haven't hit anyone in the past, any idea? Index: linux-2.6.32-rc5/drivers/scsi/libiscsi.c =================================================================== --- linux-2.6.32-rc5.orig/drivers/scsi/libiscsi.c +++ linux-2.6.32-rc5/drivers/scsi/libiscsi.c @@ -1524,7 +1524,7 @@ int iscsi_queuecommand(struct scsi_cmnd cls_session = starget_to_session(scsi_target(sc->device)); session = cls_session->dd_data; - spin_lock(&session->lock); + spin_lock_bh(&session->lock); reason = iscsi_session_chkready(cls_session); if (reason) { @@ -1610,7 +1610,7 @@ int iscsi_queuecommand(struct scsi_cmnd } session->queued_cmdsn++; - spin_unlock(&session->lock); + spin_unlock_bh(&session->lock); spin_lock(host->host_lock); return 0; @@ -1618,7 +1618,7 @@ prepd_reject: sc->scsi_done = NULL; iscsi_complete_task(task, ISCSI_TASK_COMPLETED); reject: - spin_unlock(&session->lock); + spin_unlock_bh(&session->lock); ISCSI_DBG_SESSION(session, "cmd 0x%x rejected (%d)\n", sc->cmnd[0], reason); spin_lock(host->host_lock); @@ -1628,7 +1628,7 @@ prepd_fault: sc->scsi_done = NULL; iscsi_complete_task(task, ISCSI_TASK_COMPLETED); fault: - spin_unlock(&session->lock); + spin_unlock_bh(&session->lock); ISCSI_DBG_SESSION(session, "iscsi: cmd 0x%x is not queued (%d)\n", sc->cmnd[0], reason); if (!scsi_bidi_cmnd(sc)) @@ -1638,7 +1638,7 @@ fault: scsi_in(sc)->resid = scsi_in(sc)->length; } done(sc); - spin_lock(host->host_lock); + spin_lock_bh(host->host_lock); return 0; } EXPORT_SYMBOL_GPL(iscsi_queuecommand); -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
