diff mbox series

[4/8] scsi: hisi: take blk_mq_max_nr_hw_queues() into account for calculating io vectors

Message ID 20230712125455.1986455-5-ming.lei@redhat.com
State Superseded
Headers show
Series blk-mq: fix wrong queue mapping for kdump kernel | expand

Commit Message

Ming Lei July 12, 2023, 12:54 p.m. UTC
Take blk-mq's knowledge into account for calculating io queues.

Fix wrong queue mapping in case of kdump kernel.

On arm and ppc64, 'maxcpus=1' is passed to kdump kernel command line,
see `Documentation/admin-guide/kdump/kdump.rst`, so num_possible_cpus()
still returns all CPUs because 'maxcpus=1' just bring up one single
cpu core during booting.

blk-mq sees single queue in kdump kernel, and in driver's viewpoint
there are still multiple queues, this inconsistency causes driver to apply
wrong queue mapping for handling IO, and IO timeout is triggered.

Meantime, single queue makes much less resource utilization, and reduce
risk of kernel failure.

Cc: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
index 20e1607c6282..bbec11220286 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
@@ -2550,6 +2550,9 @@  static int interrupt_preinit_v3_hw(struct hisi_hba *hisi_hba)
 
 
 	hisi_hba->cq_nvecs = vectors - BASE_VECTORS_V3_HW - hisi_hba->iopoll_q_cnt;
+	if (hisi_hba->cq_nvecs > blk_mq_max_nr_hw_queues())
+		hisi_hba->cq_nvecs = blk_mq_max_nr_hw_queues();
+
 	shost->nr_hw_queues = hisi_hba->cq_nvecs + hisi_hba->iopoll_q_cnt;
 
 	return devm_add_action(&pdev->dev, hisi_sas_v3_free_vectors, pdev);