Looks good.
Regards,
Quinn Tran
-----Original Message-----
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Date: Saturday, June 3, 2017 at 3:10 PM
To: target-devel <target-devel@xxxxxxxxxxxxxxx>
Cc: linux-scsi <linux-scsi@xxxxxxxxxxxxxxx>, lkml <linux-kernel@xxxxxxxxxxxxxxx>, Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>, "Madhani, Himanshu" <Himanshu.Madhani@xxxxxxxxxx>, "Tran, Quinn" <Quinn.Tran@xxxxxxxxxx>, Mike Christie <mchristi@xxxxxxxxxx>, Hannes Reinecke <hare@xxxxxxxx>, Christoph Hellwig <hch@xxxxxx>
Subject: [PATCH 1/3] target: Add support for TMR percpu reference counting
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch introduces TMR percpu reference counting using
se_lun->lun_ref in transport_lookup_tmr_lun(), following
how existing non TMR per se_lun reference counting works
within transport_lookup_cmd_lun().
It also adds explicit transport_lun_remove_cmd() calls to
drop the reference in the three tmr related locations that
invoke transport_cmd_check_stop_to_fabric();
- target_tmr_work() during normal ->queue_tm_rsp()
- target_complete_tmr_failure() during error ->queue_tm_rsp()
- transport_generic_handle_tmr() during early failure
Also, note the exception paths in transport_generic_free_cmd()
and transport_cmd_finish_abort() already check SCF_SE_LUN_CMD,
and will invoke transport_lun_remove_cmd() when necessary.
Cc: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
Cc: Quinn Tran <quinn.tran@xxxxxxxxxx>
Cc: Mike Christie <mchristi@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_device.c | 14 ++++++++++----
drivers/target/target_core_transport.c | 3 +++
2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 8f0e0e3..11c80c4 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -168,11 +168,20 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
rcu_read_lock();
deve = target_nacl_find_deve(nacl, unpacked_lun);
if (deve) {
- se_cmd->se_lun = rcu_dereference(deve->se_lun);
se_lun = rcu_dereference(deve->se_lun);
+
+ if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {
+ se_lun = NULL;
+ goto out_unlock;
+ }
+
+ se_cmd->se_lun = rcu_dereference(deve->se_lun);
se_cmd->pr_res_key = deve->pr_res_key;
se_cmd->orig_fe_lun = unpacked_lun;
+ se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
+ se_cmd->lun_ref_active = true;
}
+out_unlock:
rcu_read_unlock();
if (!se_lun) {
@@ -182,9 +191,6 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
unpacked_lun);
return -ENODEV;
}
- /*
- * XXX: Add percpu se_lun->lun_ref reference count for TMR
- */
se_cmd->se_dev = rcu_dereference_raw(se_lun->lun_se_dev);
se_tmr->tmr_dev = rcu_dereference_raw(se_lun->lun_se_dev);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index f16a789..83bfc97 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1588,6 +1588,7 @@ static void target_complete_tmr_failure(struct work_struct *work)
se_cmd->se_tmr_req->response = TMR_LUN_DOES_NOT_EXIST;
se_cmd->se_tfo->queue_tm_rsp(se_cmd);
+ transport_lun_remove_cmd(se_cmd);
transport_cmd_check_stop_to_fabric(se_cmd);
}
@@ -3199,6 +3200,7 @@ static void target_tmr_work(struct work_struct *work)
cmd->se_tfo->queue_tm_rsp(cmd);
check_stop:
+ transport_lun_remove_cmd(cmd);
transport_cmd_check_stop_to_fabric(cmd);
}
@@ -3221,6 +3223,7 @@ int transport_generic_handle_tmr(
pr_warn_ratelimited("handle_tmr caught CMD_T_ABORTED TMR %d"
"ref_tag: %llu tag: %llu\n", cmd->se_tmr_req->function,
cmd->se_tmr_req->ref_task_tag, cmd->tag);
+ transport_lun_remove_cmd(cmd);
transport_cmd_check_stop_to_fabric(cmd);
return 0;
}
--
1.9.1
