From 93079162bf0ed2934c7b0c3ee93ba894df8fb3cd Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 11 Dec 2013 17:06:14 +0100 Subject: [PATCH] scsi_transport_srp: Fix a race condition The rport timers must be stopped before the SRP initiator destroys the resources associated with the SCSI host. This is necessary because otherwise the callback functions invoked from the SRP transport layer could trigger a use-after-free. Stopping the rport timers before invoking scsi_remove_host() can trigger long delays in the SCSI error handler if a transport layer failure occurs while scsi_remove_host() is in progress. Hence move the code for stopping the rport timers from srp_rport_release() into a new function and invoke that function after scsi_remove_host() has finished. This patch fixes the following sporadic kernel crash: kernel BUG at include/asm-generic/dma-mapping-common.h:64! invalid opcode: 0000 [#1] SMP RIP: 0010:[] [] srp_unmap_data+0x121/0x130 [ib_srp] Call Trace: [] srp_free_req+0x3c/0x80 [ib_srp] [] srp_finish_req+0x48/0x70 [ib_srp] [] srp_terminate_io+0x4b/0x60 [ib_srp] [] __rport_fail_io_fast+0x75/0x80 [scsi_transport_srp] [] rport_fast_io_fail_timedout+0x88/0xc0 [scsi_transport_srp] [] worker_thread+0x170/0x2a0 [] kthread+0x96/0xa0 [] child_rip+0xa/0x20 Signed-off-by: Bart Van Assche Signed-off-by: Roland Dreier --- drivers/infiniband/ulp/srp/ib_srp.c | 1 + drivers/scsi/scsi_transport_srp.c | 83 +++++++++++++++-------------- include/scsi/scsi_transport_srp.h | 4 +- 3 files changed, 46 insertions(+), 42 deletions(-) diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index a88631918e85..529b6bcdca7a 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -660,6 +660,7 @@ static void srp_remove_target(struct srp_target_port *target) srp_rport_get(target->rport); srp_remove_host(target->scsi_host); scsi_remove_host(target->scsi_host); + srp_stop_rport_timers(target->rport); srp_disconnect_target(target); ib_destroy_cm_id(target->cm_id); srp_free_target_ib(target); diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c index 8b9cb22be963..a349d44c4c36 100644 --- a/drivers/scsi/scsi_transport_srp.c +++ b/drivers/scsi/scsi_transport_srp.c @@ -456,37 +456,29 @@ static void __srp_start_tl_fail_timers(struct srp_rport *rport) lockdep_assert_held(&rport->mutex); - if (!rport->deleted) { - delay = rport->reconnect_delay; - fast_io_fail_tmo = rport->fast_io_fail_tmo; - dev_loss_tmo = rport->dev_loss_tmo; - pr_debug("%s current state: %d\n", - dev_name(&shost->shost_gendev), rport->state); + delay = rport->reconnect_delay; + fast_io_fail_tmo = rport->fast_io_fail_tmo; + dev_loss_tmo = rport->dev_loss_tmo; + pr_debug("%s current state: %d\n", dev_name(&shost->shost_gendev), + rport->state); - if (delay > 0) + if (rport->state == SRP_RPORT_LOST) + return; + if (delay > 0) + queue_delayed_work(system_long_wq, &rport->reconnect_work, + 1UL * delay * HZ); + if (srp_rport_set_state(rport, SRP_RPORT_BLOCKED) == 0) { + pr_debug("%s new state: %d\n", dev_name(&shost->shost_gendev), + rport->state); + scsi_target_block(&shost->shost_gendev); + if (fast_io_fail_tmo >= 0) queue_delayed_work(system_long_wq, - &rport->reconnect_work, - 1UL * delay * HZ); - if (srp_rport_set_state(rport, SRP_RPORT_BLOCKED) == 0) { - pr_debug("%s new state: %d\n", - dev_name(&shost->shost_gendev), - rport->state); - scsi_target_block(&shost->shost_gendev); - if (fast_io_fail_tmo >= 0) - queue_delayed_work(system_long_wq, - &rport->fast_io_fail_work, - 1UL * fast_io_fail_tmo * HZ); - if (dev_loss_tmo >= 0) - queue_delayed_work(system_long_wq, - &rport->dev_loss_work, - 1UL * dev_loss_tmo * HZ); - } - } else { - pr_debug("%s has already been deleted\n", - dev_name(&shost->shost_gendev)); - srp_rport_set_state(rport, SRP_RPORT_FAIL_FAST); - scsi_target_unblock(&shost->shost_gendev, - SDEV_TRANSPORT_OFFLINE); + &rport->fast_io_fail_work, + 1UL * fast_io_fail_tmo * HZ); + if (dev_loss_tmo >= 0) + queue_delayed_work(system_long_wq, + &rport->dev_loss_work, + 1UL * dev_loss_tmo * HZ); } } @@ -560,7 +552,7 @@ int srp_reconnect_rport(struct srp_rport *rport) scsi_target_block(&shost->shost_gendev); while (scsi_request_fn_active(shost)) msleep(20); - res = i->f->reconnect(rport); + res = rport->state != SRP_RPORT_LOST ? i->f->reconnect(rport) : -ENODEV; pr_debug("%s (state %d): transport.reconnect() returned %d\n", dev_name(&shost->shost_gendev), rport->state, res); if (res == 0) { @@ -626,10 +618,6 @@ static void srp_rport_release(struct device *dev) { struct srp_rport *rport = dev_to_rport(dev); - cancel_delayed_work_sync(&rport->reconnect_work); - cancel_delayed_work_sync(&rport->fast_io_fail_work); - cancel_delayed_work_sync(&rport->dev_loss_work); - put_device(dev->parent); kfree(rport); } @@ -784,12 +772,6 @@ void srp_rport_del(struct srp_rport *rport) device_del(dev); transport_destroy_device(dev); - mutex_lock(&rport->mutex); - if (rport->state == SRP_RPORT_BLOCKED) - __rport_fail_io_fast(rport); - rport->deleted = true; - mutex_unlock(&rport->mutex); - put_device(dev); } EXPORT_SYMBOL_GPL(srp_rport_del); @@ -814,6 +796,27 @@ void srp_remove_host(struct Scsi_Host *shost) } EXPORT_SYMBOL_GPL(srp_remove_host); +/** + * srp_stop_rport_timers - stop the transport layer recovery timers + * + * Must be called after srp_remove_host() and scsi_remove_host(). The caller + * must hold a reference on the rport (rport->dev) and on the SCSI host + * (rport->dev.parent). + */ +void srp_stop_rport_timers(struct srp_rport *rport) +{ + mutex_lock(&rport->mutex); + if (rport->state == SRP_RPORT_BLOCKED) + __rport_fail_io_fast(rport); + srp_rport_set_state(rport, SRP_RPORT_LOST); + mutex_unlock(&rport->mutex); + + cancel_delayed_work_sync(&rport->reconnect_work); + cancel_delayed_work_sync(&rport->fast_io_fail_work); + cancel_delayed_work_sync(&rport->dev_loss_work); +} +EXPORT_SYMBOL_GPL(srp_stop_rport_timers); + static int srp_tsk_mgmt_response(struct Scsi_Host *shost, u64 nexus, u64 tm_id, int result) { diff --git a/include/scsi/scsi_transport_srp.h b/include/scsi/scsi_transport_srp.h index 4ebf6913b7b2..f24e763fa430 100644 --- a/include/scsi/scsi_transport_srp.h +++ b/include/scsi/scsi_transport_srp.h @@ -19,7 +19,7 @@ struct srp_rport_identifiers { * @SRP_RPORT_BLOCKED: Transport layer not operational; fast I/O fail timer * is running and I/O has been blocked. * @SRP_RPORT_FAIL_FAST: Fast I/O fail timer has expired; fail I/O fast. - * @SRP_RPORT_LOST: Device loss timer has expired; port is being removed. + * @SRP_RPORT_LOST: Port is being removed. */ enum srp_rport_state { SRP_RPORT_RUNNING, @@ -48,7 +48,6 @@ struct srp_rport { struct mutex mutex; enum srp_rport_state state; - bool deleted; int reconnect_delay; int failed_reconnects; struct delayed_work reconnect_work; @@ -101,6 +100,7 @@ extern int srp_tmo_valid(int reconnect_delay, int fast_io_fail_tmo, extern int srp_reconnect_rport(struct srp_rport *rport); extern void srp_start_tl_fail_timers(struct srp_rport *rport); extern void srp_remove_host(struct Scsi_Host *); +extern void srp_stop_rport_timers(struct srp_rport *rport); /** * srp_chkready() - evaluate the transport layer state before I/O