On 2020-09-03 12:14 p.m., Kashyap Desai wrote:
Currently io_uring support is only available in the block layer.
This RFC is to extend support of mq_poll in the scsi layer.
megaraid_sas and mpt3sas driver will be immediate users of this interface.
Both the drivers can use mq_poll only if it has exposed more than one
nr_hw_queues.
Perhaps you could add some comments in scsi_host.h about what the
int (* mq_poll)(struct Scsi_Host *shost, unsigned int queue_num);
callback should do. And you could implement it in the scsi_debug
driver which should have all the other hooks as it is part 15 of
the shared host tag support patchset.
Waiting for below changes to enable shared host tag support.
https://patchwork.kernel.org/cover/11724429/
I'm testing this at the moment. So far so good.
Doug Gilbert
Signed-off-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx>
---
drivers/scsi/scsi_lib.c | 16 ++++++++++++++++
include/scsi/scsi_cmnd.h | 1 +
include/scsi/scsi_host.h | 3 +++
3 files changed, 20 insertions(+)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 780cf084e366..7a3c59d2dfcc 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1802,6 +1802,19 @@ static void scsi_mq_exit_request(struct
blk_mq_tag_set *set, struct request *rq,
cmd->sense_buffer);
}
+
+static int scsi_mq_poll(struct blk_mq_hw_ctx *hctx)
+{
+ struct request_queue *q = hctx->queue;
+ struct scsi_device *sdev = q->queuedata;
+ struct Scsi_Host *shost = sdev->host;
+
+ if (shost->hostt->mq_poll)
+ return shost->hostt->mq_poll(shost, hctx->queue_num);
+
+ return 0;
+}
+
static int scsi_map_queues(struct blk_mq_tag_set *set)
{
struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
@@ -1869,6 +1882,7 @@ static const struct blk_mq_ops scsi_mq_ops_no_commit = {
.cleanup_rq = scsi_cleanup_rq,
.busy = scsi_mq_lld_busy,
.map_queues = scsi_map_queues,
+ .poll = scsi_mq_poll,
};
@@ -1897,6 +1911,7 @@ static const struct blk_mq_ops scsi_mq_ops = {
.cleanup_rq = scsi_cleanup_rq,
.busy = scsi_mq_lld_busy,
.map_queues = scsi_map_queues,
+ .poll = scsi_mq_poll,
};
struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
@@ -1929,6 +1944,7 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
else
tag_set->ops = &scsi_mq_ops_no_commit;
tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1;
+ tag_set->nr_maps = shost->nr_maps ? : 1;
tag_set->queue_depth = shost->can_queue;
tag_set->cmd_size = cmd_size;
tag_set->numa_node = NUMA_NO_NODE;
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index e76bac4d14c5..5844374a85b1 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -9,6 +9,7 @@
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/scatterlist.h>
+#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_request.h>
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 701f178b20ae..d34602c68d0b 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -269,6 +269,8 @@ struct scsi_host_template {
* Status: OPTIONAL
*/
int (* map_queues)(struct Scsi_Host *shost);
+
+ int (* mq_poll)(struct Scsi_Host *shost, unsigned int queue_num);
/*
* Check if scatterlists need to be padded for DMA draining.
@@ -610,6 +612,7 @@ struct Scsi_Host {
* the total queue depth is can_queue.
*/
unsigned nr_hw_queues;
+ unsigned nr_maps;
unsigned active_mode:2;
unsigned unchecked_isa_dma:1;
