From febe562c20dfa8f33bee7d419c6b517986a5aa33 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Mon, 11 Jan 2016 21:31:09 -0800 Subject: [PATCH] target: Fix LUN_RESET active I/O handling for ACK_KREF This patch fixes a NULL pointer se_cmd->cmd_kref < 0 refcount bug during TMR LUN_RESET with active se_cmd I/O, that can be triggered during se_cmd descriptor shutdown + release via core_tmr_drain_state_list() code. To address this bug, add common __target_check_io_state() helper for ABORT_TASK + LUN_RESET w/ CMD_T_COMPLETE checking, and set CMD_T_ABORTED + obtain ->cmd_kref for both cases ahead of last target_put_sess_cmd() after TFO->aborted_task() -> transport_cmd_finish_abort() callback has completed. It also introduces SCF_ACK_KREF to determine when transport_cmd_finish_abort() needs to drop the second extra reference, ahead of calling target_put_sess_cmd() for the final kref_put(&se_cmd->cmd_kref). It also updates transport_cmd_check_stop() to avoid holding se_cmd->t_state_lock while dropping se_cmd device state via target_remove_from_state_list(), now that core_tmr_drain_state_list() is holding the se_device lock while checking se_cmd state from within TMR logic. Finally, move transport_put_cmd() release of SGL + TMR + extended CDB memory into target_free_cmd_mem() in order to avoid potential resource leaks in TMR ABORT_TASK + LUN_RESET code-paths. Also update target_release_cmd_kref() accordingly. Reviewed-by: Quinn Tran Cc: Himanshu Madhani Cc: Sagi Grimberg Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Andy Grover Cc: Mike Christie Cc: stable@vger.kernel.org # 3.10+ Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_tmr.c | 69 +++++++++++++++++--------- drivers/target/target_core_transport.c | 67 +++++++++++-------------- include/target/target_core_base.h | 1 + 3 files changed, 76 insertions(+), 61 deletions(-) diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c index fcdcb117c60d..fb3decc28589 100644 --- a/drivers/target/target_core_tmr.c +++ b/drivers/target/target_core_tmr.c @@ -107,6 +107,34 @@ static int target_check_cdb_and_preempt(struct list_head *list, return 1; } +static bool __target_check_io_state(struct se_cmd *se_cmd) +{ + struct se_session *sess = se_cmd->se_sess; + + assert_spin_locked(&sess->sess_cmd_lock); + WARN_ON_ONCE(!irqs_disabled()); + /* + * If command already reached CMD_T_COMPLETE state within + * target_complete_cmd(), this se_cmd has been passed to + * fabric driver and will not be aborted. + * + * Otherwise, obtain a local se_cmd->cmd_kref now for TMR + * ABORT_TASK + LUN_RESET for CMD_T_ABORTED processing as + * long as se_cmd->cmd_kref is still active unless zero. + */ + spin_lock(&se_cmd->t_state_lock); + if (se_cmd->transport_state & CMD_T_COMPLETE) { + pr_debug("Attempted to abort io tag: %llu already complete," + " skipping\n", se_cmd->tag); + spin_unlock(&se_cmd->t_state_lock); + return false; + } + se_cmd->transport_state |= CMD_T_ABORTED; + spin_unlock(&se_cmd->t_state_lock); + + return kref_get_unless_zero(&se_cmd->cmd_kref); +} + void core_tmr_abort_task( struct se_device *dev, struct se_tmr_req *tmr, @@ -130,34 +158,22 @@ void core_tmr_abort_task( if (tmr->ref_task_tag != ref_tag) continue; - if (!kref_get_unless_zero(&se_cmd->cmd_kref)) - continue; - printk("ABORT_TASK: Found referenced %s task_tag: %llu\n", se_cmd->se_tfo->get_fabric_name(), ref_tag); - spin_lock(&se_cmd->t_state_lock); - if (se_cmd->transport_state & CMD_T_COMPLETE) { - printk("ABORT_TASK: ref_tag: %llu already complete," - " skipping\n", ref_tag); - spin_unlock(&se_cmd->t_state_lock); + if (!__target_check_io_state(se_cmd)) { spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); - target_put_sess_cmd(se_cmd); - goto out; } - se_cmd->transport_state |= CMD_T_ABORTED; - spin_unlock(&se_cmd->t_state_lock); - list_del_init(&se_cmd->se_cmd_list); spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); cancel_work_sync(&se_cmd->work); transport_wait_for_tasks(se_cmd); - target_put_sess_cmd(se_cmd); transport_cmd_finish_abort(se_cmd, true); + target_put_sess_cmd(se_cmd); printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for" " ref_tag: %llu\n", ref_tag); @@ -242,8 +258,10 @@ static void core_tmr_drain_state_list( struct list_head *preempt_and_abort_list) { LIST_HEAD(drain_task_list); + struct se_session *sess; struct se_cmd *cmd, *next; unsigned long flags; + int rc; /* * Complete outstanding commands with TASK_ABORTED SAM status. @@ -282,6 +300,16 @@ static void core_tmr_drain_state_list( if (prout_cmd == cmd) continue; + sess = cmd->se_sess; + if (WARN_ON_ONCE(!sess)) + continue; + + spin_lock(&sess->sess_cmd_lock); + rc = __target_check_io_state(cmd); + spin_unlock(&sess->sess_cmd_lock); + if (!rc) + continue; + list_move_tail(&cmd->state_list, &drain_task_list); cmd->state_active = false; } @@ -289,7 +317,7 @@ static void core_tmr_drain_state_list( while (!list_empty(&drain_task_list)) { cmd = list_entry(drain_task_list.next, struct se_cmd, state_list); - list_del(&cmd->state_list); + list_del_init(&cmd->state_list); pr_debug("LUN_RESET: %s cmd: %p" " ITT/CmdSN: 0x%08llx/0x%08x, i_state: %d, t_state: %d" @@ -313,16 +341,11 @@ static void core_tmr_drain_state_list( * loop above, but we do it down here given that * cancel_work_sync may block. */ - if (cmd->t_state == TRANSPORT_COMPLETE) - cancel_work_sync(&cmd->work); - - spin_lock_irqsave(&cmd->t_state_lock, flags); - target_stop_cmd(cmd, &flags); - - cmd->transport_state |= CMD_T_ABORTED; - spin_unlock_irqrestore(&cmd->t_state_lock, flags); + cancel_work_sync(&cmd->work); + transport_wait_for_tasks(cmd); core_tmr_handle_tas_abort(tmr_nacl, cmd, tas); + target_put_sess_cmd(cmd); } } diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 9f3608e10f25..af52f8bd8954 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -534,9 +534,6 @@ void transport_deregister_session(struct se_session *se_sess) } EXPORT_SYMBOL(transport_deregister_session); -/* - * Called with cmd->t_state_lock held. - */ static void target_remove_from_state_list(struct se_cmd *cmd) { struct se_device *dev = cmd->se_dev; @@ -561,10 +558,6 @@ static int transport_cmd_check_stop(struct se_cmd *cmd, bool remove_from_lists, { unsigned long flags; - spin_lock_irqsave(&cmd->t_state_lock, flags); - if (write_pending) - cmd->t_state = TRANSPORT_WRITE_PENDING; - if (remove_from_lists) { target_remove_from_state_list(cmd); @@ -574,6 +567,10 @@ static int transport_cmd_check_stop(struct se_cmd *cmd, bool remove_from_lists, cmd->se_lun = NULL; } + spin_lock_irqsave(&cmd->t_state_lock, flags); + if (write_pending) + cmd->t_state = TRANSPORT_WRITE_PENDING; + /* * Determine if frontend context caller is requesting the stopping of * this command for frontend exceptions. @@ -627,6 +624,8 @@ static void transport_lun_remove_cmd(struct se_cmd *cmd) void transport_cmd_finish_abort(struct se_cmd *cmd, int remove) { + bool ack_kref = (cmd->se_cmd_flags & SCF_ACK_KREF); + if (cmd->se_cmd_flags & SCF_SE_LUN_CMD) transport_lun_remove_cmd(cmd); /* @@ -638,7 +637,7 @@ void transport_cmd_finish_abort(struct se_cmd *cmd, int remove) if (transport_cmd_check_stop_to_fabric(cmd)) return; - if (remove) + if (remove && ack_kref) transport_put_cmd(cmd); } @@ -706,7 +705,7 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status) * Check for case where an explicit ABORT_TASK has been received * and transport_wait_for_tasks() will be waiting for completion.. */ - if (cmd->transport_state & CMD_T_ABORTED && + if (cmd->transport_state & CMD_T_ABORTED || cmd->transport_state & CMD_T_STOP) { spin_unlock_irqrestore(&cmd->t_state_lock, flags); complete_all(&cmd->t_transport_stop_comp); @@ -2222,20 +2221,14 @@ static inline void transport_free_pages(struct se_cmd *cmd) } /** - * transport_release_cmd - free a command - * @cmd: command to free + * transport_put_cmd - release a reference to a command + * @cmd: command to release * - * This routine unconditionally frees a command, and reference counting - * or list removal must be done in the caller. + * This routine releases our reference to the command and frees it if possible. */ -static int transport_release_cmd(struct se_cmd *cmd) +static int transport_put_cmd(struct se_cmd *cmd) { BUG_ON(!cmd->se_tfo); - - if (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) - core_tmr_release_req(cmd->se_tmr_req); - if (cmd->t_task_cdb != cmd->__t_task_cdb) - kfree(cmd->t_task_cdb); /* * If this cmd has been setup with target_get_sess_cmd(), drop * the kref and call ->release_cmd() in kref callback. @@ -2243,18 +2236,6 @@ static int transport_release_cmd(struct se_cmd *cmd) return target_put_sess_cmd(cmd); } -/** - * transport_put_cmd - release a reference to a command - * @cmd: command to release - * - * This routine releases our reference to the command and frees it if possible. - */ -static int transport_put_cmd(struct se_cmd *cmd) -{ - transport_free_pages(cmd); - return transport_release_cmd(cmd); -} - void *transport_kmap_data_sg(struct se_cmd *cmd) { struct scatterlist *sg = cmd->t_data_sg; @@ -2452,14 +2433,13 @@ static void transport_write_pending_qf(struct se_cmd *cmd) int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks) { - unsigned long flags; int ret = 0; if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD)) { if (wait_for_tasks && (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)) - transport_wait_for_tasks(cmd); + transport_wait_for_tasks(cmd); - ret = transport_release_cmd(cmd); + ret = transport_put_cmd(cmd); } else { if (wait_for_tasks) transport_wait_for_tasks(cmd); @@ -2468,11 +2448,8 @@ int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks) * has already added se_cmd to state_list, but fabric has * failed command before I/O submission. */ - if (cmd->state_active) { - spin_lock_irqsave(&cmd->t_state_lock, flags); + if (cmd->state_active) target_remove_from_state_list(cmd); - spin_unlock_irqrestore(&cmd->t_state_lock, flags); - } if (cmd->se_lun) transport_lun_remove_cmd(cmd); @@ -2517,6 +2494,16 @@ out: } EXPORT_SYMBOL(target_get_sess_cmd); +static void target_free_cmd_mem(struct se_cmd *cmd) +{ + transport_free_pages(cmd); + + if (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) + core_tmr_release_req(cmd->se_tmr_req); + if (cmd->t_task_cdb != cmd->__t_task_cdb) + kfree(cmd->t_task_cdb); +} + static void target_release_cmd_kref(struct kref *kref) { struct se_cmd *se_cmd = container_of(kref, struct se_cmd, cmd_kref); @@ -2526,17 +2513,20 @@ static void target_release_cmd_kref(struct kref *kref) spin_lock_irqsave(&se_sess->sess_cmd_lock, flags); if (list_empty(&se_cmd->se_cmd_list)) { spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); + target_free_cmd_mem(se_cmd); se_cmd->se_tfo->release_cmd(se_cmd); return; } if (se_sess->sess_tearing_down && se_cmd->cmd_wait_set) { spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); + target_free_cmd_mem(se_cmd); complete(&se_cmd->cmd_wait_comp); return; } list_del(&se_cmd->se_cmd_list); spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); + target_free_cmd_mem(se_cmd); se_cmd->se_tfo->release_cmd(se_cmd); } @@ -2548,6 +2538,7 @@ int target_put_sess_cmd(struct se_cmd *se_cmd) struct se_session *se_sess = se_cmd->se_sess; if (!se_sess) { + target_free_cmd_mem(se_cmd); se_cmd->se_tfo->release_cmd(se_cmd); return 1; } diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index 5d82816cc4e3..1a76726c45a2 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -140,6 +140,7 @@ enum se_cmd_flags_table { SCF_COMPARE_AND_WRITE = 0x00080000, SCF_COMPARE_AND_WRITE_POST = 0x00100000, SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC = 0x00200000, + SCF_ACK_KREF = 0x00400000, }; /* struct se_dev_entry->lun_flags and struct se_lun->lun_access */ -- 2.39.5