[PATCH] scsi: ufs: mcq: Limit the amount of inflight requests

[Avri Altman <avri.altman@wdc.com>]

in UFS, each request is designated via the triplet <iid, lun, task tag>.

In UFS4.0 the Initiator ID field is 8 bits wide, comprised of the
EXT_IID and IID fields. Together with the task tag (single byte), they
limit the driver's hw queues capacity.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/ufs/core/ufshcd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 35a3bd95c5e4..d529c42a682a 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -8468,6 +8468,10 @@ static int ufshcd_alloc_mcq(struct ufs_hba *hba)
 	if (ret)
 		goto err;
 
+	if (WARN_ONCE(hba->nutrs * hba->nr_hw_queues > (1 << 16) - 1,
+		     "there can be at most 1<<16 inflight requests\n"))
+		goto err;
+
 	/*
 	 * Previously allocated memory for nutrs may not be enough in MCQ mode.
 	 * Number of supported tags in MCQ mode may be larger than SDB mode.
-- 
2.17.1