[PATCH 13/20] target/iscsi: Reduce number of __iscsit_free_cmd() callers

[PATCH 13/20] target/iscsi: Reduce number of __iscsit_free_cmd() callers

[Bart Van Assche]

Instead of calling __iscsit_free_cmd() from inside iscsit_aborted_task()
if a command has been aborted and from inside iscsit_free_cmd() if a
command has not been aborted, call __iscsit_free_cmd() from inside
lio_release_cmd(). The latter function is namely called for all commands
once the reference count has dropped to zero.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Cc: Varun Prakash <varun@chelsio.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
---
 drivers/target/iscsi/iscsi_target.c          | 2 --
 drivers/target/iscsi/iscsi_target_configfs.c | 1 +
 drivers/target/iscsi/iscsi_target_util.c     | 4 +---
 3 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 8e223799347a..d547dcd625d9 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -497,8 +497,6 @@ void iscsit_aborted_task(struct iscsi_conn *conn, struct iscsi_cmd *cmd)
 	    !(cmd->se_cmd.transport_state & CMD_T_FABRIC_STOP))
 		list_del_init(&cmd->i_conn_node);
 	spin_unlock_bh(&conn->cmd_lock);
-
-	__iscsit_free_cmd(cmd, true);
 }
 EXPORT_SYMBOL(iscsit_aborted_task);
 
diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index 0ebc4818e132..0bc346b2c27c 100644
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -1546,6 +1546,7 @@ static void lio_release_cmd(struct se_cmd *se_cmd)
 	struct iscsi_cmd *cmd = container_of(se_cmd, struct iscsi_cmd, se_cmd);
 
 	pr_debug("Entering lio_release_cmd for se_cmd: %p\n", se_cmd);
+	__iscsit_free_cmd(cmd, true);
 	iscsit_release_cmd(cmd);
 }
 
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 8cfcf9033507..5a645b5f1eb4 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -772,10 +772,8 @@ void iscsit_free_cmd(struct iscsi_cmd *cmd, bool shutdown)
 	__iscsit_free_cmd(cmd, shutdown);
 	if (se_cmd) {
 		rc = transport_generic_free_cmd(se_cmd, shutdown);
-		if (!rc && shutdown && se_cmd->se_sess) {
-			__iscsit_free_cmd(cmd, shutdown);
+		if (!rc && shutdown && se_cmd->se_sess)
 			target_put_sess_cmd(se_cmd);
-		}
 	} else {
 		iscsit_release_cmd(cmd);
 	}
-- 
2.17.1

Re: [PATCH 13/20] target/iscsi: Reduce number of __iscsit_free_cmd() callers

[Varun Prakash]

On Sat, Jun 23, 2018 at 03:23:00AM +0530, Bart Van Assche wrote:
> Instead of calling __iscsit_free_cmd() from inside iscsit_aborted_task()
> if a command has been aborted and from inside iscsit_free_cmd() if a
> command has not been aborted, call __iscsit_free_cmd() from inside
> lio_release_cmd(). The latter function is namely called for all commands
> once the reference count has dropped to zero.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
> Reviewed-by: Mike Christie <mchristi@redhat.com>
> Cc: Varun Prakash <varun@chelsio.com>
> Cc: Hannes Reinecke <hare@suse.com>
> Cc: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/target/iscsi/iscsi_target.c          | 2 --
>  drivers/target/iscsi/iscsi_target_configfs.c | 1 +
>  drivers/target/iscsi/iscsi_target_util.c     | 4 +---
>  3 files changed, 2 insertions(+), 5 deletions(-)
> 

Hi Bart,

cxgbit driver is not working with this patch as transport_free_pages()
is called before calling conn->conn_transport->iscsit_release_cmd(), cxgbit
driver calls dma_unmap_sg() in ->iscsit_release_cmd(), transport_free_pages()
frees the scatterlist pages so dma unmap will not work.

cxgbit driver needs a callback before target frees the pages
so that it can dma unmap.

We can remove ->iscsit_release_cmd() from __iscsit_free_cmd() and call it
directly from iscsit_free_cmd(), iscsit_aborted_task().    

Thanks
Varun 

Re: [PATCH 13/20] target/iscsi: Reduce number of __iscsit_free_cmd() callers

[Bart Van Assche]

On Thu, 2018-07-26 at 16:42 +-0530, Varun Prakash wrote:
+AD4- cxgbit driver is not working with this patch as transport+AF8-free+AF8-pages()
+AD4- is called before calling conn-+AD4-conn+AF8-transport-+AD4-iscsit+AF8-release+AF8-cmd(), cxgbit
+AD4- driver calls dma+AF8-unmap+AF8-sg() in -+AD4-iscsit+AF8-release+AF8-cmd(), transport+AF8-free+AF8-pages()
+AD4- frees the scatterlist pages so dma unmap will not work.
+AD4- 
+AD4- cxgbit driver needs a callback before target frees the pages
+AD4- so that it can dma unmap.
+AD4- 
+AD4- We can remove -+AD4-iscsit+AF8-release+AF8-cmd() from +AF8AXw-iscsit+AF8-free+AF8-cmd() and call it
+AD4- directly from iscsit+AF8-free+AF8-cmd(), iscsit+AF8-aborted+AF8-task().    

Hello Varun,

Thank you for your report. Since no other patches in this series depend on
this patch, I will send a revert.

Bart.