| Message ID | 20211018135753.15297-1-d.bogdanov@yadro.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 12b6fcd0ea7f3cb7c3b34668fc678779924123ae |
| Headers | show |
| Series | [v4] target: core: remove from tmr_list at lun unlink | expand |
On 10/18/21 8:57 AM, Dmitry Bogdanov wrote: > Currently TMF commands are removed from de_device.dev_tmf_list at > the very end of se_cmd lifecycle. But se_lun unlinks from se_cmd > up on a command status (response) is queued in transport layer. > It means that LUN and backend device can be deleted meantime and at > the moment of repsonse completion a panic is occured: > > target_tmr_work() > cmd->se_tfo->queue_tm_rsp(cmd); // send abort_rsp to a wire > transport_lun_remove_cmd(cmd) // unlink se_cmd from se_lun > - // - // - // - > <<<--- lun remove > <<<--- core backend device remove > - // - // - // - > qlt_handle_abts_completion() > tfo->free_mcmd() > transport_generic_free_cmd() > target_put_sess_cmd() > core_tmr_release_req() { > if (dev) { // backend device, can not be null > spin_lock_irqsave(&dev->se_tmr_lock, flags); //<<<--- CRASH > > Call Trace: > NIP [c000000000e1683c] _raw_spin_lock_irqsave+0x2c/0xc0 > LR [c00800000e433338] core_tmr_release_req+0x40/0xa0 [target_core_mod] > Call Trace: > (unreliable) > 0x0 > target_put_sess_cmd+0x2a0/0x370 [target_core_mod] > transport_generic_free_cmd+0x6c/0x1b0 [target_core_mod] > tcm_qla2xxx_complete_mcmd+0x28/0x50 [tcm_qla2xxx] > process_one_work+0x2c4/0x5c0 > worker_thread+0x88/0x690 > > For FC protocol it is a race condition, but for iSCSI protocol it is > easyly reproduced by manual sending iSCSI commands: > - Send some SCSI sommand > - Send Abort of that command over iSCSI > - Remove LUN on target > - Send next iSCSI command to acknowledge the Abort_Response > - target panics > > There is no sense to keep the command in tmr_list until response > completion, so move the removal from tmr_list from the response > completion to the response queueing when lun is unlinked. > Move the removal from state list too as it is a subject to the same > race condition. > > Fixes: c66ac9db8d4a ("[SCSI] target: Add LIO target core v4.0.0-rc6") > Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com> > Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com> > > --- > v4: > remove superfluous transport_lookup_tmr_lun that could race with lun > reset > v3: > remove iscsi fix as not related to the issue > avoid double removal from tmr_list > v2: > fix stuck in tmr list in error case > > The issue exists from the very begining. > I uploaded a scapy script that helps to reproduce the issue at > https://gist.github.com/logost/cb93df41dd2432454324449b390403c4 Reviewed-by: Mike Christie <michael.christie@oracle.com>
Dmitry, > Currently TMF commands are removed from de_device.dev_tmf_list at the > very end of se_cmd lifecycle. But se_lun unlinks from se_cmd up on a > command status (response) is queued in transport layer. It means that > LUN and backend device can be deleted meantime and at the moment of > repsonse completion a panic is occured: Applied to 5.16/scsi-staging, thanks!
diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c index e7fcbc09f9db..bac111456fa1 100644 --- a/drivers/target/target_core_tmr.c +++ b/drivers/target/target_core_tmr.c @@ -50,15 +50,6 @@ EXPORT_SYMBOL(core_tmr_alloc_req); void core_tmr_release_req(struct se_tmr_req *tmr) { - struct se_device *dev = tmr->tmr_dev; - unsigned long flags; - - if (dev) { - spin_lock_irqsave(&dev->se_tmr_lock, flags); - list_del_init(&tmr->tmr_list); - spin_unlock_irqrestore(&dev->se_tmr_lock, flags); - } - kfree(tmr); } @@ -156,13 +147,6 @@ void core_tmr_abort_task( se_cmd->state_active = false; spin_unlock_irqrestore(&dev->queues[i].lock, flags); - /* - * Ensure that this ABORT request is visible to the LU - * RESET code. - */ - if (!tmr->tmr_dev) - WARN_ON_ONCE(transport_lookup_tmr_lun(tmr->task_cmd) < 0); - if (dev->transport->tmr_notify) dev->transport->tmr_notify(dev, TMR_ABORT_TASK, &aborted_list); @@ -234,6 +218,7 @@ static void core_tmr_drain_tmr_list( } list_move_tail(&tmr_p->tmr_list, &drain_tmr_list); + tmr_p->tmr_dev = NULL; } spin_unlock_irqrestore(&dev->se_tmr_lock, flags); diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 14c6f2bb1b01..e60abd230e90 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -676,6 +676,21 @@ static void target_remove_from_state_list(struct se_cmd *cmd) spin_unlock_irqrestore(&dev->queues[cmd->cpuid].lock, flags); } +static void target_remove_from_tmr_list(struct se_cmd *cmd) +{ + struct se_device *dev = NULL; + unsigned long flags; + + if (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) + dev = cmd->se_tmr_req->tmr_dev; + + if (dev) { + spin_lock_irqsave(&dev->se_tmr_lock, flags); + if (cmd->se_tmr_req->tmr_dev) + list_del_init(&cmd->se_tmr_req->tmr_list); + spin_unlock_irqrestore(&dev->se_tmr_lock, flags); + } +} /* * This function is called by the target core after the target core has * finished processing a SCSI command or SCSI TMF. Both the regular command @@ -687,13 +702,6 @@ static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd) { unsigned long flags; - target_remove_from_state_list(cmd); - - /* - * Clear struct se_cmd->se_lun before the handoff to FE. - */ - cmd->se_lun = NULL; - spin_lock_irqsave(&cmd->t_state_lock, flags); /* * Determine if frontend context caller is requesting the stopping of @@ -728,8 +736,16 @@ static void transport_lun_remove_cmd(struct se_cmd *cmd) if (!lun) return; + target_remove_from_state_list(cmd); + target_remove_from_tmr_list(cmd); + if (cmpxchg(&cmd->lun_ref_active, true, false)) percpu_ref_put(&lun->lun_ref); + + /* + * Clear struct se_cmd->se_lun before the handoff to FE. + */ + cmd->se_lun = NULL; } static void target_complete_failure_work(struct work_struct *work)
Currently TMF commands are removed from de_device.dev_tmf_list at the very end of se_cmd lifecycle. But se_lun unlinks from se_cmd up on a command status (response) is queued in transport layer. It means that LUN and backend device can be deleted meantime and at the moment of repsonse completion a panic is occured: target_tmr_work() cmd->se_tfo->queue_tm_rsp(cmd); // send abort_rsp to a wire transport_lun_remove_cmd(cmd) // unlink se_cmd from se_lun - // - // - // - <<<--- lun remove <<<--- core backend device remove - // - // - // - qlt_handle_abts_completion() tfo->free_mcmd() transport_generic_free_cmd() target_put_sess_cmd() core_tmr_release_req() { if (dev) { // backend device, can not be null spin_lock_irqsave(&dev->se_tmr_lock, flags); //<<<--- CRASH Call Trace: NIP [c000000000e1683c] _raw_spin_lock_irqsave+0x2c/0xc0 LR [c00800000e433338] core_tmr_release_req+0x40/0xa0 [target_core_mod] Call Trace: (unreliable) 0x0 target_put_sess_cmd+0x2a0/0x370 [target_core_mod] transport_generic_free_cmd+0x6c/0x1b0 [target_core_mod] tcm_qla2xxx_complete_mcmd+0x28/0x50 [tcm_qla2xxx] process_one_work+0x2c4/0x5c0 worker_thread+0x88/0x690 For FC protocol it is a race condition, but for iSCSI protocol it is easyly reproduced by manual sending iSCSI commands: - Send some SCSI sommand - Send Abort of that command over iSCSI - Remove LUN on target - Send next iSCSI command to acknowledge the Abort_Response - target panics There is no sense to keep the command in tmr_list until response completion, so move the removal from tmr_list from the response completion to the response queueing when lun is unlinked. Move the removal from state list too as it is a subject to the same race condition. Fixes: c66ac9db8d4a ("[SCSI] target: Add LIO target core v4.0.0-rc6") Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com> Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com> --- v4: remove superfluous transport_lookup_tmr_lun that could race with lun reset v3: remove iscsi fix as not related to the issue avoid double removal from tmr_list v2: fix stuck in tmr list in error case The issue exists from the very begining. I uploaded a scapy script that helps to reproduce the issue at https://gist.github.com/logost/cb93df41dd2432454324449b390403c4 --- drivers/target/target_core_tmr.c | 17 +-------------- drivers/target/target_core_transport.c | 30 ++++++++++++++++++++------ 2 files changed, 24 insertions(+), 23 deletions(-)