[PATCH 5.16 055/227] scsi: core: Reallocate devices budget map on queue depth change

Greg Kroah-Hartman
2022-02-21T09:51:08Z

From: Ming Lei <ming.lei@redhat.com>

[ Upstream commit edb854a3680bacc9ef9b91ec0c5ff6105886f6f3 ]

We currently use ->cmd_per_lun as initial queue depth for setting up the
budget_map. Martin Wilck reported that it is common for the queue_depth to
be subsequently updated in slave_configure() based on detected hardware
characteristics.

As a result, for some drivers, the static host template settings for
cmd_per_lun and can_queue won't actually get used in practice. And if the
default values are used to allocate the budget_map, memory may be consumed
unnecessarily.

Fix the issue by reallocating the budget_map after ->slave_configure()
returns. At that time the device queue_depth should accurately reflect what
the hardware needs.

Link: https://lore.kernel.org/r/20220127153733.409132-1-ming.lei@redhat.com
Cc: Bart Van Assche <bvanassche@acm.org>
Reported-by: Martin Wilck <martin.wilck@suse.com>
Suggested-by: Martin Wilck <martin.wilck@suse.com>
Tested-by: Martin Wilck <mwilck@suse.com>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/scsi_scan.c | 55 ++++++++++++++++++++++++++++++++++++----
1 file changed, 50 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 23e1c0acdeaee..d0ce723299bf7 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -214,6 +214,48 @@ static void scsi_unlock_floptical(struct scsi_device *sdev,
SCSI_TIMEOUT, 3, NULL);
}

+static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
+ unsigned int depth)
+{
+ int new_shift = sbitmap_calculate_shift(depth);
+ bool need_alloc = !sdev->budget_map.map;
+ bool need_free = false;
+ int ret;
+ struct sbitmap sb_backup;
+
+ /*
+ * realloc if new shift is calculated, which is caused by setting
+ * up one new default queue depth after calling ->slave_configure
+ */
+ if (!need_alloc && new_shift != sdev->budget_map.shift)
+ need_alloc = need_free = true;
+
+ if (!need_alloc)
+ return 0;
+
+ /*
+ * Request queue has to be frozen for reallocating budget map,
+ * and here disk isn't added yet, so freezing is pretty fast
+ */
+ if (need_free) {
+ blk_mq_freeze_queue(sdev->request_queue);
+ sb_backup = sdev->budget_map;
+ }
+ ret = sbitmap_init_node(&sdev->budget_map,
+ scsi_device_max_queue_depth(sdev),
+ new_shift, GFP_KERNEL,
+ sdev->request_queue->node, false, true);
+ if (need_free) {
+ if (ret)
+ sdev->budget_map = sb_backup;
+ else
+ sbitmap_free(&sb_backup);
+ ret = 0;
+ blk_mq_unfreeze_queue(sdev->request_queue);
+ }
+ return ret;
+}
+
/**
* scsi_alloc_sdev - allocate and setup a scsi_Device
* @starget: which target to allocate a &scsi_device for
@@ -306,11 +348,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
* default device queue depth to figure out sbitmap shift
* since we use this queue depth most of times.
*/
- if (sbitmap_init_node(&sdev->budget_map,
- scsi_device_max_queue_depth(sdev),
- sbitmap_calculate_shift(depth),
- GFP_KERNEL, sdev->request_queue->node,
- false, true)) {
+ if (scsi_realloc_sdev_budget_map(sdev, depth)) {
put_device(&starget->dev);
kfree(sdev);
goto out;
@@ -1017,6 +1055,13 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
}
return SCSI_SCAN_NO_RESPONSE;
}
+
+ /*
+ * The queue_depth is often changed in ->slave_configure.
+ * Set up budget map again since memory consumption of
+ * the map depends on actual queue depth.
+ */
+ scsi_realloc_sdev_budget_map(sdev, sdev->queue_depth);
}

if (sdev->scsi_level >= SCSI_3)
--
2.34.1