On 5/30/19 5:28 PM, John Garry wrote:
On 29/05/2019 14:28, Hannes Reinecke wrote:
From: Hannes Reinecke <hare@xxxxxxxx>
Allocate a separate 'reserved_cmd_q' for sending reserved commands.
Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
---
drivers/scsi/scsi_lib.c | 15 ++++++++++++++-
include/scsi/scsi_host.h | 4 ++++
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e17153a9ce7c..076459853622 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1831,6 +1831,7 @@ struct request_queue *scsi_mq_alloc_queue(struct
scsi_device *sdev)
int scsi_mq_setup_tags(struct Scsi_Host *shost)
{
unsigned int cmd_size, sgl_size;
+ int ret;
sgl_size = scsi_mq_inline_sgl_size(shost);
cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size +
sgl_size;
@@ -1850,11 +1851,23 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
shost->tag_set.driver_data = shost;
- return blk_mq_alloc_tag_set(&shost->tag_set);
+ ret = blk_mq_alloc_tag_set(&shost->tag_set);
+ if (ret)
+ return ret;
+
+ if (shost->nr_reserved_cmds && shost->use_reserved_cmd_q) {
+ shost->reserved_cmd_q = blk_mq_init_queue(&shost->tag_set);
+ if (IS_ERR(shost->reserved_cmd_q)) {
+ blk_mq_free_tag_set(&shost->tag_set);
+ ret = PTR_ERR(shost->reserved_cmd_q);
+ }
+ }
+ return ret;
}
void scsi_mq_destroy_tags(struct Scsi_Host *shost)
{
+ blk_cleanup_queue(shost->reserved_cmd_q);
blk_mq_free_tag_set(&shost->tag_set);
}
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 89998b6bee04..a2bab5f07eff 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -600,6 +600,7 @@ struct Scsi_Host {
* Number of reserved commands, if any.
*/
unsigned nr_reserved_cmds;
+ struct request_queue *reserved_cmd_q;
unsigned active_mode:2;
unsigned unchecked_isa_dma:1;
@@ -637,6 +638,9 @@ struct Scsi_Host {
/* The transport requires the LUN bits NOT to be stored in CDB[1] */
unsigned no_scsi2_lun_in_cdb:1;
+ /* Host requires a separate reserved_cmd_q */
+ unsigned use_reserved_cmd_q:1;
Is this really required? I would think that a non-zero value for
shost->nr_reserved_cmds means the same thing in practice.
;
My implementation actually allows for per-device reserved tags (eg for
virtio). But some drivers require to use internal commands prior to any
device setup, so they have to use a separate reserved command queue just
to be able to allocate tags.
So yes, they are required.
Cheers,
Hannes
