On 2020-10-15 9:37 a.m., Kashyap Desai wrote:
Add support of iouring iopoll interface in scsi_debug.
This feature requires shared hosttag support in kernel and driver.
I am continuing to test this patch. There is one fix shown inline below
plus a question near the end.
Doug Gilbert
Signed-off-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx>
Cc: dgilbert@xxxxxxxxxxxx
Cc: linux-block@xxxxxxxxxxxxxxx
---
drivers/scsi/scsi_debug.c | 123 ++++++++++++++++++++++++++++++++++++++
1 file changed, 123 insertions(+)
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index a87e40aec11f..4d9cc6af588c 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -826,6 +826,7 @@ static int sdeb_zbc_max_open = DEF_ZBC_MAX_OPEN_ZONES;
static int sdeb_zbc_nr_conv = DEF_ZBC_NR_CONV_ZONES;
static int submit_queues = DEF_SUBMIT_QUEUES; /* > 1 for multi-queue (mq) */
+static int poll_queues; /* iouring iopoll interface.*/
static struct sdebug_queue *sdebug_q_arr; /* ptr to array of submit queues */
static DEFINE_RWLOCK(atomic_rw);
@@ -5422,6 +5423,14 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
cmnd->host_scribble = (unsigned char *)sqcp;
sd_dp = sqcp->sd_dp;
spin_unlock_irqrestore(&sqp->qc_lock, iflags);
+
+ /* Do not complete IO from default completion path.
+ * Let it to be on queue.
+ * Completion should happen from mq_poll interface.
+ */
+ if ((sqp - sdebug_q_arr) >= (submit_queues - poll_queues))
+ return 0;
+
if (!sd_dp) {
sd_dp = kzalloc(sizeof(*sd_dp), GFP_ATOMIC);
if (!sd_dp) {
@@ -5604,6 +5613,7 @@ module_param_named(sector_size, sdebug_sector_size, int, S_IRUGO);
module_param_named(statistics, sdebug_statistics, bool, S_IRUGO | S_IWUSR);
module_param_named(strict, sdebug_strict, bool, S_IRUGO | S_IWUSR);
module_param_named(submit_queues, submit_queues, int, S_IRUGO);
+module_param_named(poll_queues, poll_queues, int, S_IRUGO);
module_param_named(tur_ms_to_ready, sdeb_tur_ms_to_ready, int, S_IRUGO);
module_param_named(unmap_alignment, sdebug_unmap_alignment, int, S_IRUGO);
module_param_named(unmap_granularity, sdebug_unmap_granularity, int, S_IRUGO);
@@ -5673,6 +5683,7 @@ MODULE_PARM_DESC(sector_size, "logical block size in bytes (def=512)");
MODULE_PARM_DESC(statistics, "collect statistics on commands, queues (def=0)");
MODULE_PARM_DESC(strict, "stricter checks: reserved field in cdb (def=0)");
MODULE_PARM_DESC(submit_queues, "support for block multi-queue (def=1)");
+MODULE_PARM_DESC(poll_queues, "support for iouring iopoll queues");
MODULE_PARM_DESC(tur_ms_to_ready, "TEST UNIT READY millisecs before initial good status (def=0)");
MODULE_PARM_DESC(unmap_alignment, "lowest aligned thin provisioning lba (def=0)");
MODULE_PARM_DESC(unmap_granularity, "thin provisioning granularity in blocks (def=1)");
@@ -7140,6 +7151,104 @@ static int resp_not_ready(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
return check_condition_result;
}
+static int sdebug_map_queues(struct Scsi_Host *shost)
+{
+ int i, qoff;
+
+ if (shost->nr_hw_queues == 1)
+ return 0;
+
+ for (i = 0, qoff = 0; i < HCTX_MAX_TYPES; i++) {
+ struct blk_mq_queue_map *map = &shost->tag_set.map[i];
+
+ map->nr_queues = 0;
+
+ if (i == HCTX_TYPE_DEFAULT)
+ map->nr_queues = submit_queues - poll_queues;
+ else if (i == HCTX_TYPE_POLL)
+ map->nr_queues = poll_queues;
+
+ if (!map->nr_queues) {
+ BUG_ON(i == HCTX_TYPE_DEFAULT);
+ continue;
+ }
+
+ map->queue_offset = qoff;
+ blk_mq_map_queues(map);
+
+ qoff += map->nr_queues;
+ }
+
+ return 0;
+
+}
+
+static int sdebug_blk_mq_poll(struct Scsi_Host *shost, unsigned int queue_num)
+{
+ int qc_idx;
+ int retiring = 0;
+ unsigned long iflags;
+ struct sdebug_queue *sqp;
+ struct sdebug_queued_cmd *sqcp;
+ struct scsi_cmnd *scp;
+ struct sdebug_dev_info *devip;
+ int num_entries = 0;
+
+ sqp = sdebug_q_arr + queue_num;
+
+ do {
+ spin_lock_irqsave(&sqp->qc_lock, iflags);
+ qc_idx = find_first_bit(sqp->in_use_bm, sdebug_max_queue);
+ if (unlikely((qc_idx < 0) || (qc_idx >= SDEBUG_CANQUEUE)))
The above line IMO needs to be:
if (unlikely((qc_idx < 0) || (qc_idx >= sdebug_max_queue)))
If not, when sdebug_max_queue < SDEBUG_CANQUEUE and there is no request waiting
then "scp is NULL, ..." is reported suggesting there is an error.
+ goto out;
+
+ sqcp = &sqp->qc_arr[qc_idx];
+ scp = sqcp->a_cmnd;
+ if (unlikely(scp == NULL)) {
+ pr_err("scp is NULL, queue_num=%d, qc_idx=%d from %s\n",
+ queue_num, qc_idx, __func__);
+ goto out;
+ }
+ devip = (struct sdebug_dev_info *)scp->device->hostdata;
+ if (likely(devip))
+ atomic_dec(&devip->num_in_q);
+ else
+ pr_err("devip=NULL from %s\n", __func__);
+ if (unlikely(atomic_read(&retired_max_queue) > 0))
+ retiring = 1;
+
+ sqcp->a_cmnd = NULL;
+ if (unlikely(!test_and_clear_bit(qc_idx, sqp->in_use_bm))) {
+ pr_err("Unexpected completion sqp %p queue_num=%d qc_idx=%d from %s\n",
+ sqp, queue_num, qc_idx, __func__);
+ goto out;
+ }
+
+ if (unlikely(retiring)) { /* user has reduced max_queue */
+ int k, retval;
+
+ retval = atomic_read(&retired_max_queue);
+ if (qc_idx >= retval) {
+ pr_err("index %d too large\n", retval);
+ goto out;
+ }
+ k = find_last_bit(sqp->in_use_bm, retval);
+ if ((k < sdebug_max_queue) || (k == retval))
+ atomic_set(&retired_max_queue, 0);
+ else
+ atomic_set(&retired_max_queue, k + 1);
+ }
+ spin_unlock_irqrestore(&sqp->qc_lock, iflags);
+ scp->scsi_done(scp); /* callback to mid level */
+ num_entries++;
+ } while (1);
+
+out:
+ spin_unlock_irqrestore(&sqp->qc_lock, iflags);
+ return num_entries;
+}
+
+
static int scsi_debug_queuecommand(struct Scsi_Host *shost,
struct scsi_cmnd *scp)
{
@@ -7318,6 +7427,8 @@ static struct scsi_host_template sdebug_driver_template = {
.ioctl = scsi_debug_ioctl,
.queuecommand = scsi_debug_queuecommand,
.change_queue_depth = sdebug_change_qdepth,
+ .map_queues = sdebug_map_queues,
+ .mq_poll = sdebug_blk_mq_poll,
.eh_abort_handler = scsi_debug_abort,
.eh_device_reset_handler = scsi_debug_device_reset,
.eh_target_reset_handler = scsi_debug_target_reset,
@@ -7365,6 +7476,18 @@ static int sdebug_driver_probe(struct device *dev)
if (sdebug_host_max_queue)
hpnt->host_tagset = 1;
+ /* poll queues are possible for nr_hw_queues > 1 */
+ if (hpnt->nr_hw_queues == 1)
+ poll_queues = 0;
+
+ /* poll queues */
+ if (poll_queues >= submit_queues) {
So the above line rules out poll_queues == submit_queues; is that the
intention? If so, a short explanation of why in a comment would be
helpful. Helpful at least to me who would like to document this option.
+ pr_warn("%s: trim poll_queues to 1\n", my_name);
+ poll_queues = 1;
+ }
+ if (poll_queues)
+ hpnt->nr_maps = 3;
+
sdbg_host->shost = hpnt;
*((struct sdebug_host_info **)hpnt->hostdata) = sdbg_host;
if ((hpnt->this_id >= 0) && (sdebug_num_tgts > hpnt->this_id))
