[PATCH V3 12/14] scsi: ufs: limit max allowed nr_hw_queues

[Ming Lei]

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 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.

Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
 drivers/ufs/core/ufs-mcq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c
index 6fb0e007af63..7d808836b018 100644
--- a/drivers/ufs/core/ufs-mcq.c
+++ b/drivers/ufs/core/ufs-mcq.c
@@ -186,7 +186,7 @@ static int ufshcd_mcq_config_nr_queues(struct ufs_hba *hba)
 
 	if (!hba->nr_queues[HCTX_TYPE_DEFAULT])
 		hba->nr_queues[HCTX_TYPE_DEFAULT] = min3(rem, rw_queues,
-							 num_possible_cpus());
+							 scsi_max_nr_hw_queues());
 
 	for (i = 0; i < HCTX_MAX_TYPES; i++)
 		host->nr_hw_queues += hba->nr_queues[i];
-- 
2.40.1