Target drivers must call target_sess_cmd_list_set_waiting() and
target_wait_for_sess_cmds() before freeing a session. Since freeing
a session is only safe after all commands that are associated with
a session have finished, make target_wait_for_sess_cmds() also wait
for commands that are being aborted. Instead of setting a flag in
each pending command from target_sess_cmd_list_set_waiting() and
waiting in target_wait_for_sess_cmds() on a per-command completion,
only set a per-session flag in the former function and wait on
a per-session completion in the latter function. This change is
safe because once a SCSI initiator system has submitted a command
a target system is always allowed to execute it to completion. See
also commit 0f4a943168f3 ("target: Fix remote-port TMR ABORT +
se_cmd fabric stop").
This patch is based on the following two patches:
* Bart Van Assche, target: Simplify session shutdown code, February 19, 2015
(https://github.com/bvanassche/linux/commit/8df5463d7d7619f2f1b70cfe5172eaef0aa52815).
* Christoph Hellwig, target: Rework session shutdown code, December 7, 2015
(http://thread.gmane.org/gmane.linux.scsi.target.devel/10695).
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Mike Christie <mchristi@xxxxxxxxxx>
Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
---
drivers/target/target_core_tmr.c | 5 +-
drivers/target/target_core_transport.c | 84 +++++++++++-----------------------
include/target/target_core_base.h | 3 +-
3 files changed, 29 insertions(+), 63 deletions(-)
diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 9c7bc1ca341a..da8125dd3a4c 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -142,7 +142,7 @@ static bool __target_check_io_state(struct se_cmd *se_cmd,
return false;
}
}
- if (sess->sess_tearing_down || se_cmd->cmd_wait_set) {
+ if (sess->sess_tearing_down) {
pr_debug("Attempted to abort io tag: %llu already shutdown,"
" skipping\n", se_cmd->tag);
spin_unlock(&se_cmd->t_state_lock);
@@ -187,7 +187,6 @@ void core_tmr_abort_task(
if (!__target_check_io_state(se_cmd, se_sess, 0))
continue;
- list_del_init(&se_cmd->se_cmd_list);
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
cancel_work_sync(&se_cmd->work);
@@ -259,7 +258,7 @@ static void core_tmr_drain_tmr_list(
spin_unlock(&sess->sess_cmd_lock);
continue;
}
- if (sess->sess_tearing_down || cmd->cmd_wait_set) {
+ if (sess->sess_tearing_down) {
spin_unlock(&cmd->t_state_lock);
spin_unlock(&sess->sess_cmd_lock);
continue;
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index f649cf0bed75..ad975e038b10 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -237,8 +237,8 @@ struct se_session *transport_init_session(enum target_prot_op sup_prot_ops)
INIT_LIST_HEAD(&se_sess->sess_list);
INIT_LIST_HEAD(&se_sess->sess_acl_list);
INIT_LIST_HEAD(&se_sess->sess_cmd_list);
- INIT_LIST_HEAD(&se_sess->sess_wait_list);
spin_lock_init(&se_sess->sess_cmd_lock);
+ init_waitqueue_head(&se_sess->cmd_list_wq);
se_sess->sup_prot_ops = sup_prot_ops;
return se_sess;
@@ -2664,20 +2664,23 @@ static void target_release_cmd_kref(struct kref *kref)
if (se_sess) {
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
+ if (likely(!list_empty(&se_cmd->se_cmd_list))) {
+ list_del(&se_cmd->se_cmd_list);
+ if (list_empty(&se_sess->sess_cmd_list))
+ wake_up(&se_sess->cmd_list_wq);
+ }
spin_lock(&se_cmd->t_state_lock);
fabric_stop = (se_cmd->transport_state & CMD_T_FABRIC_STOP) &&
(se_cmd->transport_state & CMD_T_ABORTED);
spin_unlock(&se_cmd->t_state_lock);
- if (se_cmd->cmd_wait_set || fabric_stop) {
- list_del_init(&se_cmd->se_cmd_list);
+ if (fabric_stop) {
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
target_free_cmd_mem(se_cmd);
complete(&se_cmd->cmd_wait_comp);
return;
}
- list_del_init(&se_cmd->se_cmd_list);
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
}
@@ -2800,77 +2803,42 @@ void target_show_cmd(const char *pfx, struct se_cmd *cmd)
}
EXPORT_SYMBOL(target_show_cmd);
-/* target_sess_cmd_list_set_waiting - Flag all commands in
- * sess_cmd_list to complete cmd_wait_comp. Set
- * sess_tearing_down so no more commands are queued.
+/**
+ * target_sess_cmd_list_set_waiting - Set sess_tearing_down so no new commands are queued.
* @se_sess: session to flag
*/
void target_sess_cmd_list_set_waiting(struct se_session *se_sess)
{
- struct se_cmd *se_cmd, *tmp_cmd;
unsigned long flags;
- int rc;
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
- if (se_sess->sess_tearing_down) {
- spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
- return;
- }
se_sess->sess_tearing_down = 1;
- list_splice_init(&se_sess->sess_cmd_list, &se_sess->sess_wait_list);
-
- list_for_each_entry_safe(se_cmd, tmp_cmd,
- &se_sess->sess_wait_list, se_cmd_list) {
- rc = kref_get_unless_zero(&se_cmd->cmd_kref);
- if (rc) {
- se_cmd->cmd_wait_set = 1;
- spin_lock(&se_cmd->t_state_lock);
- se_cmd->transport_state |= CMD_T_FABRIC_STOP;
- spin_unlock(&se_cmd->t_state_lock);
- } else
- list_del_init(&se_cmd->se_cmd_list);
- }
-
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
}
EXPORT_SYMBOL(target_sess_cmd_list_set_waiting);
-/* target_wait_for_sess_cmds - Wait for outstanding descriptors
+/**
+ * target_wait_for_sess_cmds - Wait for outstanding commands
* @se_sess: session to wait for active I/O
*/
void target_wait_for_sess_cmds(struct se_session *se_sess)
{
- struct se_cmd *se_cmd, *tmp_cmd;
- unsigned long flags;
- bool tas;
-
- list_for_each_entry_safe(se_cmd, tmp_cmd,
- &se_sess->sess_wait_list, se_cmd_list) {
- pr_debug("Waiting for se_cmd: %p t_state: %d, fabric state:"
- " %d\n", se_cmd, se_cmd->t_state,
- se_cmd->se_tfo->get_cmd_state(se_cmd));
-
- spin_lock_irqsave(&se_cmd->t_state_lock, flags);
- tas = (se_cmd->transport_state & CMD_T_TAS);
- spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);
-
- if (!target_put_sess_cmd(se_cmd)) {
- if (tas)
- target_put_sess_cmd(se_cmd);
- }
-
- wait_for_completion(&se_cmd->cmd_wait_comp);
- pr_debug("After cmd_wait_comp: se_cmd: %p t_state: %d"
- " fabric state: %d\n", se_cmd, se_cmd->t_state,
- se_cmd->se_tfo->get_cmd_state(se_cmd));
-
- se_cmd->se_tfo->release_cmd(se_cmd);
- }
-
- spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
- WARN_ON(!list_empty(&se_sess->sess_cmd_list));
- spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
+ struct se_cmd *cmd;
+ int ret;
+ WARN_ON_ONCE(!se_sess->sess_tearing_down);
+
+ spin_lock_irq(&se_sess->sess_cmd_lock);
+ do {
+ ret = wait_event_interruptible_lock_irq_timeout(
+ se_sess->cmd_list_wq,
+ list_empty(&se_sess->sess_cmd_list),
+ se_sess->sess_cmd_lock, 180 * HZ);
+ list_for_each_entry(cmd, &se_sess->sess_cmd_list, se_cmd_list)
+ target_show_cmd("session shutdown: still waiting for ",
+ cmd);
+ } while (ret <= 0);
+ spin_unlock_irq(&se_sess->sess_cmd_lock);
}
EXPORT_SYMBOL(target_wait_for_sess_cmds);
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 9f9f5902af38..b9fb73f2dcbb 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -442,7 +442,6 @@ struct se_cmd {
u8 scsi_asc;
u8 scsi_ascq;
u16 scsi_sense_length;
- unsigned cmd_wait_set:1;
unsigned unknown_data_length:1;
bool state_active:1;
u64 tag; /* SAM command identifier aka task tag */
@@ -604,8 +603,8 @@ struct se_session {
struct list_head sess_list;
struct list_head sess_acl_list;
struct list_head sess_cmd_list;
- struct list_head sess_wait_list;
spinlock_t sess_cmd_lock;
+ wait_queue_head_t cmd_list_wq;
void *sess_cmd_map;
struct percpu_ida sess_tag_pool;
};
--
2.16.2
--
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