Re: [PATCH 20/31] scsi: Only add commands to the device command list if required by the LLD

[Hannes Reinecke]

On 05/24/2017 02:34 AM, Bart Van Assche wrote:
> Just like for the scsi-mq code path, in the single queue SCSI code
> path only add commands to the per-device command list if required
> by the SCSI LLD. This patch will make it easier to merge the
> single-queue and multiqueue command initialization code.
> 
> Signed-off-by: Bart Van Assche 
> Reviewed-by: Christoph Hellwig 
> Cc: Hannes Reinecke 
> ---
>  drivers/scsi/scsi.c  |  9 +
>  drivers/scsi/scsi_lib.c  | 52 
> +---
>  drivers/scsi/scsi_priv.h |  2 ++
>  3 files changed, 35 insertions(+), 28 deletions(-)
> 
Reviewed-by: Hannes Reinecke 

Cheers,

Hannes
-- 
Dr. Hannes ReineckeTeamlead Storage & Networking
h...@suse.de   +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

[PATCH 20/31] scsi: Only add commands to the device command list if required by the LLD

[Bart Van Assche]

Just like for the scsi-mq code path, in the single queue SCSI code
path only add commands to the per-device command list if required
by the SCSI LLD. This patch will make it easier to merge the
single-queue and multiqueue command initialization code.

Signed-off-by: Bart Van Assche 
Reviewed-by: Christoph Hellwig 
Cc: Hannes Reinecke 
---
 drivers/scsi/scsi.c  |  9 +
 drivers/scsi/scsi_lib.c  | 52 +---
 drivers/scsi/scsi_priv.h |  2 ++
 3 files changed, 35 insertions(+), 28 deletions(-)

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 7bfbcfa7af40..485684aafb9b 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -108,14 +108,7 @@ EXPORT_SYMBOL(scsi_sd_pm_domain);
  */
 void scsi_put_command(struct scsi_cmnd *cmd)
 {
-   unsigned long flags;
-
-   /* serious error if the command hasn't come from a device list */
-   spin_lock_irqsave(>device->list_lock, flags);
-   BUG_ON(list_empty(>list));
-   list_del_init(>list);
-   spin_unlock_irqrestore(>device->list_lock, flags);
-
+   scsi_del_cmd_from_list(cmd);
BUG_ON(delayed_work_pending(>abort_work));
 }
 
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 31d2b9cd20e5..5e2f26524475 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -582,19 +582,9 @@ static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
 
 static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
 {
-   struct scsi_device *sdev = cmd->device;
-   struct Scsi_Host *shost = sdev->host;
-   unsigned long flags;
-
scsi_mq_free_sgtables(cmd);
scsi_uninit_cmd(cmd);
-
-   if (shost->use_cmd_list) {
-   BUG_ON(list_empty(>list));
-   spin_lock_irqsave(>list_lock, flags);
-   list_del_init(>list);
-   spin_unlock_irqrestore(>list_lock, flags);
-   }
+   scsi_del_cmd_from_list(cmd);
 }
 
 /*
@@ -1132,6 +1122,35 @@ int scsi_init_io(struct scsi_cmnd *cmd)
 }
 EXPORT_SYMBOL(scsi_init_io);
 
+/* Add a command to the list used by the aacraid and dpt_i2o drivers */
+void scsi_add_cmd_to_list(struct scsi_cmnd *cmd)
+{
+   struct scsi_device *sdev = cmd->device;
+   struct Scsi_Host *shost = sdev->host;
+   unsigned long flags;
+
+   if (shost->use_cmd_list) {
+   spin_lock_irqsave(>list_lock, flags);
+   list_add_tail(>list, >cmd_list);
+   spin_unlock_irqrestore(>list_lock, flags);
+   }
+}
+
+/* Remove a command from the list used by the aacraid and dpt_i2o drivers */
+void scsi_del_cmd_from_list(struct scsi_cmnd *cmd)
+{
+   struct scsi_device *sdev = cmd->device;
+   struct Scsi_Host *shost = sdev->host;
+   unsigned long flags;
+
+   if (shost->use_cmd_list) {
+   spin_lock_irqsave(>list_lock, flags);
+   BUG_ON(list_empty(>list));
+   list_del_init(>list);
+   spin_unlock_irqrestore(>list_lock, flags);
+   }
+}
+
 /* Called from inside blk_get_request() */
 static void scsi_initialize_rq(struct request *rq)
 {
@@ -1145,7 +1164,6 @@ void scsi_init_command(struct scsi_device *dev, struct 
scsi_cmnd *cmd)
 {
void *buf = cmd->sense_buffer;
void *prot = cmd->prot_sdb;
-   unsigned long flags;
 
/* zero out the cmd, except for the embedded scsi_request */
memset((char *)cmd + sizeof(cmd->req), 0,
@@ -1157,9 +1175,7 @@ void scsi_init_command(struct scsi_device *dev, struct 
scsi_cmnd *cmd)
INIT_DELAYED_WORK(>abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies;
 
-   spin_lock_irqsave(>list_lock, flags);
-   list_add_tail(>list, >cmd_list);
-   spin_unlock_irqrestore(>list_lock, flags);
+   scsi_add_cmd_to_list(cmd);
 }
 
 static int scsi_setup_scsi_cmnd(struct scsi_device *sdev, struct request *req)
@@ -1874,11 +1890,7 @@ static int scsi_mq_prep_fn(struct request *req)
INIT_DELAYED_WORK(>abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies;
 
-   if (shost->use_cmd_list) {
-   spin_lock_irq(>list_lock);
-   list_add_tail(>list, >cmd_list);
-   spin_unlock_irq(>list_lock);
-   }
+   scsi_add_cmd_to_list(cmd);
 
sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
cmd->sdb.table.sgl = sg;
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index f86057842f9a..c11c1f9c912c 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -80,6 +80,8 @@ int scsi_eh_get_sense(struct list_head *work_q,
 int scsi_noretry_cmd(struct scsi_cmnd *scmd);
 
 /* scsi_lib.c */
+extern void scsi_add_cmd_to_list(struct scsi_cmnd *cmd);
+extern void scsi_del_cmd_from_list(struct scsi_cmnd *cmd);
 extern int scsi_maybe_unblock_host(struct scsi_device *sdev);
 extern void scsi_device_unbusy(struct scsi_device