crypto: hisilicon/qm - prevent soft lockup in receive loop

[ Upstream commit 33fc506 ]

In the scenario where the accelerator business is fully loaded.
When the workqueue receiving messages and performing callback
processing, there are a large number of messages that need to be
received, and there are continuously messages that have been
processed and need to be received.
This will cause the receive loop here to be locked for a long time.
This scenario will cause watchdog timeout problems on OS with kernel
preemption turned off.

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

Therefore, it is necessary to add an actively scheduled operation in the
while loop to prevent this problem.
After adding it, no matter whether the OS turns on or off the kernel
preemption function. Neither will cause watchdog timeout issues.

Signed-off-by: Longfang Liu <liulongfang@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/crypto/hisilicon/qm.c

@@ -841,6 +841,8 @@ 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 */