This reference count keeps track of the number of references held
by a target driver on a command. se_cmd.complete is set once the
target driver has released all references it held on a command.
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Andy Grover <agrover@xxxxxxxxxx>
Cc: David Disseldorp <ddiss@xxxxxxx>
---
drivers/target/target_core_internal.h | 1 +
drivers/target/target_core_tmr.c | 8 ++++----
drivers/target/target_core_transport.c | 24 +++++++++++++++++++++---
include/target/target_core_base.h | 2 ++
4 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index 9ab7090f7c83..48de996ad28d 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -146,6 +146,7 @@ int transport_dump_vpd_assoc(struct t10_vpd *, unsigned char *, int);
int transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int);
int transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int);
void transport_clear_lun_ref(struct se_lun *);
+int __target_put_sess_cmd(struct se_cmd *se_cmd);
void transport_send_task_abort(struct se_cmd *);
sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size);
void target_qf_do_work(struct work_struct *work);
diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 367799b4dde1..161c8b8482db 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -188,7 +188,7 @@ void core_tmr_abort_task(
if (!tmr->tmr_dev &&
transport_lookup_tmr_lun(tmr->task_cmd,
se_cmd->orig_fe_lun) < 0) {
- target_put_sess_cmd(se_cmd);
+ __target_put_sess_cmd(se_cmd);
continue;
}
@@ -199,7 +199,7 @@ void core_tmr_abort_task(
transport_wait_for_tasks(se_cmd);
transport_cmd_finish_abort(se_cmd, true);
- target_put_sess_cmd(se_cmd);
+ __target_put_sess_cmd(se_cmd);
printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for"
" ref_tag: %llu\n", ref_tag);
@@ -299,7 +299,7 @@ static void core_tmr_drain_tmr_list(
transport_wait_for_tasks(cmd);
transport_cmd_finish_abort(cmd, 1);
- target_put_sess_cmd(cmd);
+ __target_put_sess_cmd(cmd);
}
}
@@ -398,7 +398,7 @@ static void core_tmr_drain_state_list(
transport_wait_for_tasks(cmd);
core_tmr_handle_tas_abort(cmd, tas);
- target_put_sess_cmd(cmd);
+ __target_put_sess_cmd(cmd);
}
}
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 8f2169e92771..533b584c2806 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1217,6 +1217,7 @@ void transport_init_se_cmd(
init_completion(&cmd->cmd_wait_comp);
spin_lock_init(&cmd->t_state_lock);
kref_init(&cmd->cmd_kref);
+ atomic_set(&cmd->tgt_ref, 1);
cmd->transport_state = CMD_T_DEV_ACTIVE;
cmd->se_tfo = tfo;
@@ -2554,6 +2555,7 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref)
if (!kref_get_unless_zero(&se_cmd->cmd_kref))
return -EINVAL;
+ atomic_inc(&se_cmd->tgt_ref);
se_cmd->se_cmd_flags |= SCF_ACK_KREF;
}
@@ -2590,6 +2592,8 @@ static void target_release_cmd_kref(struct kref *kref)
unsigned long flags;
bool fabric_stop;
+ WARN_ON_ONCE(atomic_read(&se_cmd->tgt_ref) != 0);
+
if (se_sess) {
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
@@ -2614,15 +2618,29 @@ static void target_release_cmd_kref(struct kref *kref)
}
/**
+ * __target_put_sess_cmd - drop a reference obtained by kref_get_unless_zero()
+ */
+int __target_put_sess_cmd(struct se_cmd *se_cmd)
+{
+ return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref);
+}
+
+/**
* target_put_sess_cmd - decrease the command reference count
- * @se_cmd: command to drop a reference from
+ * @se_cmd: Drop a reference obtained by target_get_sess_cmd().
*
* Returns 1 if and only if this target_put_sess_cmd() call caused the
* refcount to drop to zero. Returns zero otherwise.
*/
int target_put_sess_cmd(struct se_cmd *se_cmd)
{
- return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref);
+ long ref = atomic_dec_return(&se_cmd->tgt_ref);
+
+ WARN_ON_ONCE(ref < 0);
+ if (ref == 0)
+ complete(&se_cmd->complete);
+
+ return __target_put_sess_cmd(se_cmd);
}
EXPORT_SYMBOL(target_put_sess_cmd);
@@ -2680,7 +2698,7 @@ void target_wait_for_sess_cmds(struct se_session *se_sess)
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 (!__target_put_sess_cmd(se_cmd)) {
if (tas)
target_put_sess_cmd(se_cmd);
}
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index fb87f0e5d0d6..c84e5eecb94d 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -495,7 +495,9 @@ struct se_cmd {
#define CMD_T_FABRIC_STOP (1 << 11)
spinlock_t t_state_lock;
struct kref cmd_kref;
+ atomic_t tgt_ref;
struct completion t_transport_stop_comp;
+ struct completion complete;
struct work_struct work;
--
2.11.0
--
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