[PATCH 5/7] crypto: hisilicon/qm - prevent soft lockup in qm_poll_req_cb()'s loop

[Weili Qian]

The function qm_poll_req_cb() may take a while due to complex req_cb,
so soft lockup may occur in kernel with preemption disabled.

The error logs:
watchdog: BUG: soft lockup - CPU#23 stuck for 23s! [kworker/u262:1:1407]
[ 1461.978428][   C23] Call trace:
[ 1461.981890][   C23]  complete+0x8c/0xf0
[ 1461.986031][   C23]  kcryptd_async_done+0x154/0x1f4 [dm_crypt]
[ 1461.992154][   C23]  sec_skcipher_callback+0x7c/0xf4 [hisi_sec2]
[ 1461.998446][   C23]  sec_req_cb+0x104/0x1f4 [hisi_sec2]
[ 1462.003950][   C23]  qm_poll_req_cb+0xcc/0x150 [hisi_qm]
[ 1462.009531][   C23]  qm_work_process+0x60/0xc0 [hisi_qm]
[ 1462.015101][   C23]  process_one_work+0x1c4/0x470
[ 1462.020052][   C23]  worker_thread+0x150/0x3c4
[ 1462.024735][   C23]  kthread+0x108/0x13c
[ 1462.028889][   C23]  ret_from_fork+0x10/0x18

Add a cond_resched() to prevent that.

Signed-off-by: Weili Qian <qianweili@xxxxxxxxxx>
---
 drivers/crypto/hisilicon/qm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/crypto/hisilicon/qm.c b/drivers/crypto/hisilicon/qm.c
index 2d0080b546e8..cc2caa08966d 100644
--- a/drivers/crypto/hisilicon/qm.c
+++ b/drivers/crypto/hisilicon/qm.c
@@ -954,6 +954,8 @@ static void qm_poll_req_cb(struct hisi_qp *qp)
 		qm_db(qm, qp->qp_id, QM_DOORBELL_CMD_CQ,
 		      qp->qp_status.cq_head, 0);
 		atomic_dec(&qp->qp_status.used);
+
+		cond_resched();
 	}
 
 	/* set c_flag */
-- 
2.33.0