[PATCH-v2 0/3] target: Fix LUN_RESET active I/O + TMR handling

[PATCH-v2 0/3] target: Fix LUN_RESET active I/O + TMR handling

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

Hi folks,

Here is -v2 series to address two LUN_RESET active
I/O + TMR se_cmd->cmd_kref < 0 bugs as reported
recently by Quinn & Co.  This bug can occur during
active I/O remote port TMR LUN_RESET with multi-port
LIO configurations.

To address this bug, it adds __target_check_io_state()
common handler for ABORT_TASK + LUN_RESET I/O abort
cases, and moves remaining se_cmd SGL page + release
into target_free_cmd_mem() to now be called directly
from the final target_release_cmd_kref() callback.

Following __target_check_io_state(), it also obtains
kref_get_unless_zero(&se_cmd->cmd_kref) for TMR descs
during LUN_RESET in core_tmr_drain_tmr_list(), in order
to utilize common transport_wait_for_tasks() code when
se_cmd + se_tmr_req descriptors are being aborted or
shutdown.

At this point the changes are able to survive multi-port
active I/O LUN_RESET using iscsi-target ports against
Linux + ESX hosts with TAS=1.

Note there is still a known issue wrt multi-port active
I/O LUN_RESET when se_session shutdown occurs at the
same time, that I'm still groking and will need to be
addressed for -v3 code.

Quinn + Co, please have a look at qla2xxx + TAS with
this series when you've got a moment, and let us know
how active I/O LUN_RESET works with your test-case.

Thank you,

--nab

v2 changes:
   - Fix TAS handling for multi-session se_node_acls
   - Change target_complete_cmd() to check for ABORTED || STOP
   - Avoid calling target_remove_from_state_list() with
     se_cmd->t_state_lock held in transport_cmd_check_stop()
   - Add missing target_free_cmd_mem() in target_put_sess_cmd()
     special case.
   - Add a more useful __target_check_io_state() comment
   - Use assert_spin_locked() + WARN_ON_ONCE() when necessary
   - Drop unnecessary !list_empty check

Nicholas Bellinger (3):
  target: Fix LUN_RESET active I/O handling for ACK_KREF
  target: Fix LUN_RESET active TMR descriptor handling
  target: Fix TAS handling for multi-session se_node_acls

 drivers/target/target_core_tmr.c       | 104 ++++++++++++++++++++++++---------
 drivers/target/target_core_transport.c |  73 ++++++++++++++---------
 include/target/target_core_base.h      |   1 +
 3 files changed, 122 insertions(+), 56 deletions(-)

-- 
1.9.1

[PATCH-v2 1/3] target: Fix LUN_RESET active I/O handling for ACK_KREF

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

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.

Cc: Quinn Tran <quinn.tran@qlogic.com>
Cc: Himanshu Madhani <himanshu.madhani@qlogic.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Andy Grover <agrover@redhat.com>
Cc: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/target_core_tmr.c       | 66 ++++++++++++++++++++++++----------
 drivers/target/target_core_transport.c | 56 ++++++++++++++---------------
 include/target/target_core_base.h      |  1 +
 3 files changed, 75 insertions(+), 48 deletions(-)

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 7137042..5f315b4 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(&se_session->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,
@@ -133,26 +161,18 @@ void core_tmr_abort_task(
 		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);
 			goto out;
 		}
-		se_cmd->transport_state |= CMD_T_ABORTED;
-		spin_unlock(&se_cmd->t_state_lock);
-
 		list_del_init(&se_cmd->se_cmd_list);
-		kref_get(&se_cmd->cmd_kref);
 		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);
@@ -237,8 +257,10 @@ 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.
@@ -277,6 +299,17 @@ 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) {
+			printk("LUN_RESET I/O: non-zero kref_get_unless_zero\n");
+			continue;
+		}
 		list_move_tail(&cmd->state_list, &drain_task_list);
 		cmd->state_active = false;
 	}
@@ -284,7 +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"
@@ -308,16 +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 a7c1bb5..19500e3 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -561,10 +561,6 @@ 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 +570,10 @@ 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 +627,8 @@ 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 +640,7 @@ 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 +708,7 @@ 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);
@@ -2220,20 +2222,14 @@ 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.
@@ -2241,18 +2237,6 @@ 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;
@@ -2457,7 +2441,7 @@ int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
 		if (wait_for_tasks && (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB))
 			 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);
@@ -2515,6 +2499,16 @@ 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)
 		__releases(&se_cmd->se_sess->sess_cmd_lock)
 {
@@ -2523,17 +2517,20 @@ static void target_release_cmd_kref(struct kref *kref)
 
 	if (list_empty(&se_cmd->se_cmd_list)) {
 		spin_unlock(&se_sess->sess_cmd_lock);
+		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(&se_sess->sess_cmd_lock);
+		target_free_cmd_mem(se_cmd);
 		complete(&se_cmd->cmd_wait_comp);
 		return;
 	}
 	list_del(&se_cmd->se_cmd_list);
 	spin_unlock(&se_sess->sess_cmd_lock);
 
+	target_free_cmd_mem(se_cmd);
 	se_cmd->se_tfo->release_cmd(se_cmd);
 }
 
@@ -2545,6 +2542,7 @@ 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 a4bed07..1060c52 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 */
-- 
1.9.1

[PATCH-v2 2/3] target: Fix LUN_RESET active TMR descriptor handling

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

This patch fixes a NULL pointer se_cmd->cmd_kref < 0
refcount bug during TMR LUN_RESET with active TMRs,
triggered during se_cmd + se_tmr_req descriptor
shutdown + release via core_tmr_drain_tmr_list().

To address this bug, go ahead and obtain a local
kref_get_unless_zero(&se_cmd->cmd_kref) for active I/O
to set CMD_T_ABORTED, and transport_wait_for_tasks()
followed by the final target_put_sess_cmd() to drop
the local ->cmd_kref.

Also add two new checks within target_tmr_work() to
avoid CMD_T_ABORTED -> TFO->queue_tm_rsp() callbacks
ahead of invoking the backend -> fabric put in
transport_cmd_check_stop_to_fabric().

For good measure, also change core_tmr_release_req()
to use list_del_init() ahead of se_tmr_req memory
free.

Cc: Quinn Tran <quinn.tran@qlogic.com>
Cc: Himanshu Madhani <himanshu.madhani@qlogic.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Andy Grover <agrover@redhat.com>
Cc: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/target_core_tmr.c       | 22 +++++++++++++++++++++-
 drivers/target/target_core_transport.c | 17 +++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 5f315b4..d4f30aa 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -68,7 +68,7 @@ void core_tmr_release_req(struct se_tmr_req *tmr)
 
 	if (dev) {
 		spin_lock_irqsave(&dev->se_tmr_lock, flags);
-		list_del(&tmr->tmr_list);
+		list_del_init(&tmr->tmr_list);
 		spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
 	}
 
@@ -193,9 +193,11 @@ static void core_tmr_drain_tmr_list(
 	struct list_head *preempt_and_abort_list)
 {
 	LIST_HEAD(drain_tmr_list);
+	struct se_session *sess;
 	struct se_tmr_req *tmr_p, *tmr_pp;
 	struct se_cmd *cmd;
 	unsigned long flags;
+	bool rc;
 	/*
 	 * Release all pending and outgoing TMRs aside from the received
 	 * LUN_RESET tmr..
@@ -221,17 +223,31 @@ static void core_tmr_drain_tmr_list(
 		if (target_check_cdb_and_preempt(preempt_and_abort_list, cmd))
 			continue;
 
+		sess = cmd->se_sess;
+		if (WARN_ON_ONCE(!sess))
+			continue;
+
+		spin_lock(&sess->sess_cmd_lock);
 		spin_lock(&cmd->t_state_lock);
 		if (!(cmd->transport_state & CMD_T_ACTIVE)) {
 			spin_unlock(&cmd->t_state_lock);
+			spin_unlock(&sess->sess_cmd_lock);
 			continue;
 		}
 		if (cmd->t_state == TRANSPORT_ISTATE_PROCESSING) {
 			spin_unlock(&cmd->t_state_lock);
+			spin_unlock(&sess->sess_cmd_lock);
 			continue;
 		}
+		cmd->transport_state |= CMD_T_ABORTED;
 		spin_unlock(&cmd->t_state_lock);
 
+		rc = kref_get_unless_zero(&cmd->cmd_kref);
+		spin_unlock(&sess->sess_cmd_lock);
+		if (!rc) {
+			printk("LUN_RESET TMR: non-zero kref_get_unless_zero\n");
+			continue;
+		}
 		list_move_tail(&tmr_p->tmr_list, &drain_tmr_list);
 	}
 	spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
@@ -245,7 +261,11 @@ static void core_tmr_drain_tmr_list(
 			(preempt_and_abort_list) ? "Preempt" : "", tmr_p,
 			tmr_p->function, tmr_p->response, cmd->t_state);
 
+		cancel_work_sync(&cmd->work);
+		transport_wait_for_tasks(cmd);
+
 		transport_cmd_finish_abort(cmd, 1);
+		target_put_sess_cmd(cmd);
 	}
 }
 
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 19500e3..6235067 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2905,8 +2905,17 @@ static void target_tmr_work(struct work_struct *work)
 	struct se_cmd *cmd = container_of(work, struct se_cmd, work);
 	struct se_device *dev = cmd->se_dev;
 	struct se_tmr_req *tmr = cmd->se_tmr_req;
+	unsigned long flags;
 	int ret;
 
+	spin_lock_irqsave(&cmd->t_state_lock, flags);
+	if (cmd->transport_state & CMD_T_ABORTED) {
+		tmr->response = TMR_FUNCTION_REJECTED;
+		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+		goto check_stop;
+	}
+	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+
 	switch (tmr->function) {
 	case TMR_ABORT_TASK:
 		core_tmr_abort_task(dev, tmr, cmd->se_sess);
@@ -2939,9 +2948,17 @@ static void target_tmr_work(struct work_struct *work)
 		break;
 	}
 
+	spin_lock_irqsave(&cmd->t_state_lock, flags);
+	if (cmd->transport_state & CMD_T_ABORTED) {
+		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+		goto check_stop;
+	}
 	cmd->t_state = TRANSPORT_ISTATE_PROCESSING;
+	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+
 	cmd->se_tfo->queue_tm_rsp(cmd);
 
+check_stop:
 	transport_cmd_check_stop_to_fabric(cmd);
 }
 
-- 
1.9.1

[PATCH-v2 3/3] target: Fix TAS handling for multi-session se_node_acls

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

This patch fixes a bug in TMR task aborted status (TAS)
handling when multiple sessions are connected to the
same target WWPN endpoint and se_node_acl descriptor,
resulting in TASK_ABORTED status to not be generated
for aborted se_cmds on the remote port.

This is due to core_tmr_handle_tas_abort() incorrectly
comparing se_node_acl instead of se_session, for which
the multi-session case is expected to be sharing the
same se_node_acl.

Instead, go ahead and update core_tmr_handle_tas_abort()
to compare tmr_sess + cmd->se_sess in order to determine
if the LUN_RESET was received on a different I_T nexus,
and TASK_ABORTED status response needs to be generated.

Cc: Quinn Tran <quinn.tran@qlogic.com>
Cc: Himanshu Madhani <himanshu.madhani@qlogic.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Andy Grover <agrover@redhat.com>
Cc: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/target_core_tmr.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index d4f30aa..3eff563 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -76,7 +76,7 @@ void core_tmr_release_req(struct se_tmr_req *tmr)
 }
 
 static void core_tmr_handle_tas_abort(
-	struct se_node_acl *tmr_nacl,
+	struct se_session *tmr_sess,
 	struct se_cmd *cmd,
 	int tas)
 {
@@ -84,7 +84,7 @@ static void core_tmr_handle_tas_abort(
 	/*
 	 * TASK ABORTED status (TAS) bit support
 	 */
-	if ((tmr_nacl && (tmr_nacl != cmd->se_sess->se_node_acl)) && tas) {
+	if ((tmr_sess && (tmr_sess != cmd->se_sess)) && tas) {
 		remove = false;
 		transport_send_task_abort(cmd);
 	}
@@ -111,7 +111,7 @@ static bool __target_check_io_state(struct se_cmd *se_cmd)
 {
 	struct se_session *sess = se_cmd->se_sess;
 
-	assert_spin_locked(&se_session->sess_cmd_lock);
+	assert_spin_locked(&sess->sess_cmd_lock);
 	WARN_ON_ONCE(!irqs_disabled());
 	/*
 	 * If command already reached CMD_T_COMPLETE state within
@@ -272,7 +272,7 @@ static void core_tmr_drain_tmr_list(
 static void core_tmr_drain_state_list(
 	struct se_device *dev,
 	struct se_cmd *prout_cmd,
-	struct se_node_acl *tmr_nacl,
+	struct se_session *tmr_sess,
 	int tas,
 	struct list_head *preempt_and_abort_list)
 {
@@ -364,7 +364,7 @@ static void core_tmr_drain_state_list(
 		cancel_work_sync(&cmd->work);
 		transport_wait_for_tasks(cmd);
 
-		core_tmr_handle_tas_abort(tmr_nacl, cmd, tas);
+		core_tmr_handle_tas_abort(tmr_sess, cmd, tas);
 		target_put_sess_cmd(cmd);
 	}
 }
@@ -377,6 +377,7 @@ int core_tmr_lun_reset(
 {
 	struct se_node_acl *tmr_nacl = NULL;
 	struct se_portal_group *tmr_tpg = NULL;
+	struct se_session *tmr_sess = NULL;
 	int tas;
         /*
 	 * TASK_ABORTED status bit, this is configurable via ConfigFS
@@ -395,8 +396,9 @@ int core_tmr_lun_reset(
 	 * or struct se_device passthrough..
 	 */
 	if (tmr && tmr->task_cmd && tmr->task_cmd->se_sess) {
-		tmr_nacl = tmr->task_cmd->se_sess->se_node_acl;
-		tmr_tpg = tmr->task_cmd->se_sess->se_tpg;
+		tmr_sess = tmr->task_cmd->se_sess;
+		tmr_nacl = tmr_sess->se_node_acl;
+		tmr_tpg = tmr_sess->se_tpg;
 		if (tmr_nacl && tmr_tpg) {
 			pr_debug("LUN_RESET: TMR caller fabric: %s"
 				" initiator port %s\n",
@@ -409,7 +411,7 @@ int core_tmr_lun_reset(
 		dev->transport->name, tas);
 
 	core_tmr_drain_tmr_list(dev, tmr, preempt_and_abort_list);
-	core_tmr_drain_state_list(dev, prout_cmd, tmr_nacl, tas,
+	core_tmr_drain_state_list(dev, prout_cmd, tmr_sess, tas,
 				preempt_and_abort_list);
 
 	/*
-- 
1.9.1

Re: [PATCH-v2 1/3] target: Fix LUN_RESET active I/O handling for ACK_KREF

[Christoph Hellwig]

> +static bool __target_check_io_state(struct se_cmd *se_cmd)
> +{
> +	struct se_session *sess = se_cmd->se_sess;
> +
> +	assert_spin_locked(&se_session->sess_cmd_lock);
> +	WARN_ON_ONCE(!irqs_disabled());

Btw, I looked a the code and can't really see what sess_cmd_lock is
supposed to protect here.

> +		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) {
> +			printk("LUN_RESET I/O: non-zero kref_get_unless_zero\n");
> +			continue;
> +		}

And thus why we care about taking it here.

Re: [PATCH-v2 2/3] target: Fix LUN_RESET active TMR descriptor handling

[Christoph Hellwig]

> +		sess = cmd->se_sess;
> +		if (WARN_ON_ONCE(!sess))
> +			continue;
> +
> +		spin_lock(&sess->sess_cmd_lock);
>  		spin_lock(&cmd->t_state_lock);
>  		if (!(cmd->transport_state & CMD_T_ACTIVE)) {
>  			spin_unlock(&cmd->t_state_lock);
> +			spin_unlock(&sess->sess_cmd_lock);
>  			continue;
>  		}
>  		if (cmd->t_state == TRANSPORT_ISTATE_PROCESSING) {
>  			spin_unlock(&cmd->t_state_lock);
> +			spin_unlock(&sess->sess_cmd_lock);
>  			continue;
>  		}
> +		cmd->transport_state |= CMD_T_ABORTED;
>  		spin_unlock(&cmd->t_state_lock);
>  
> +		rc = kref_get_unless_zero(&cmd->cmd_kref);
> +		spin_unlock(&sess->sess_cmd_lock);

Similar to the previous patch I don't understand the need for
sess_cmd_lock here.

> +	spin_lock_irqsave(&cmd->t_state_lock, flags);
> +	if (cmd->transport_state & CMD_T_ABORTED) {
> +		tmr->response = TMR_FUNCTION_REJECTED;
> +		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
> +		goto check_stop;
> +	}
> +	spin_unlock_irqrestore(&cmd->t_state_lock, flags);

Taking a lock for checking a single bit is pointless.

Re: [PATCH-v2 3/3] target: Fix TAS handling for multi-session se_node_acls

[Christoph Hellwig]

> -	if ((tmr_nacl && (tmr_nacl != cmd->se_sess->se_node_acl)) && tas) {
> +	if ((tmr_sess && (tmr_sess != cmd->se_sess)) && tas) {

Care to drop the pointless braces here if you touch this anyway?

	if (tmr_sess && tmr_sess != cmd->se_sess && tas)

Otherwise this looks fine to me:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH-v2 1/3] target: Fix LUN_RESET active I/O handling for ACK_KREF

[Nicholas A. Bellinger]

On Tue, 2016-01-26 at 18:19 +0100, Christoph Hellwig wrote:
> > +static bool __target_check_io_state(struct se_cmd *se_cmd)
> > +{
> > +	struct se_session *sess = se_cmd->se_sess;
> > +
> > +	assert_spin_locked(&se_session->sess_cmd_lock);
> > +	WARN_ON_ONCE(!irqs_disabled());
> 
> Btw, I looked a the code and can't really see what sess_cmd_lock is
> supposed to protect here.
> 
> > +		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) {
> > +			printk("LUN_RESET I/O: non-zero kref_get_unless_zero\n");
> > +			continue;
> > +		}
> 
> And thus why we care about taking it here.

I'm still working on -v3 series to handle se_session shutdown during
this specific multi-port LUN_RESET case, and considering using the
existing se_cmd->cmd_wait_set bit to signal when this special case
happens.

Currently ->sess_cmd_lock is held in target_release_cmd_kref() and
target_sess_cmd_list_set_waiting() while checking and setting this
value.

Re: [PATCH-v2 1/3] target: Fix LUN_RESET active I/O handling for ACK_KREF

[Sagi Grimberg]

> +		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) {
> +			printk("LUN_RESET I/O: non-zero kref_get_unless_zero\n");

Is this message always correct? __target_check_io_state() will return
false for commands that were completed..