[PATCH 10/18] scsi: Only add commands to the device command list if required by the LLD

Bart Van Assche
2017-05-19T18:30:25Z

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 <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
---
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(&cmd->device->list_lock, flags);
- BUG_ON(list_empty(&cmd->list));
- list_del_init(&cmd->list);
- spin_unlock_irqrestore(&cmd->device->list_lock, flags);
-
+ scsi_del_cmd_from_list(cmd);
BUG_ON(delayed_work_pending(&cmd->abort_work));
}

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index efa5741cab02..a8d4f17ad5aa 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -583,19 +583,9 @@ 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(&cmd->list));
- spin_lock_irqsave(&sdev->list_lock, flags);
- list_del_init(&cmd->list);
- spin_unlock_irqrestore(&sdev->list_lock, flags);
- }
+ scsi_del_cmd_from_list(cmd);
}

/*
@@ -1133,6 +1123,35 @@ 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(&sdev->list_lock, flags);
+ list_add_tail(&cmd->list, &sdev->cmd_list);
+ spin_unlock_irqrestore(&sdev->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(&sdev->list_lock, flags);
+ BUG_ON(list_empty(&cmd->list));
+ list_del_init(&cmd->list);
+ spin_unlock_irqrestore(&sdev->list_lock, flags);
+ }
+}
+
/* Called from inside blk_get_request() */
static void scsi_initialize_rq(struct request *rq)
{
@@ -1146,7 +1165,6 @@ 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,
@@ -1158,9 +1176,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies;

- spin_lock_irqsave(&dev->list_lock, flags);
- list_add_tail(&cmd->list, &dev->cmd_list);
- spin_unlock_irqrestore(&dev->list_lock, flags);
+ scsi_add_cmd_to_list(cmd);
}

static int scsi_setup_scsi_cmnd(struct scsi_device *sdev, struct request *req)
@@ -1875,11 +1891,7 @@ static int scsi_mq_prep_fn(struct request *req)
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies;

- if (shost->use_cmd_list) {
- spin_lock_irq(&sdev->list_lock);
- list_add_tail(&cmd->list, &sdev->cmd_list);
- spin_unlock_irq(&sdev->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 *sdev);
extern void scsi_queue_insert(struct scsi_cmnd *cmd, int reason);
--
2.12.2