scsi: ufs: Fix imbalanced scsi_block_reqs_cnt caused by ufshcd_hold()

The scsi_block_reqs_cnt increased in ufshcd_hold() is supposed to be
decreased back in ufshcd_ungate_work() in a paired way. However, if
specific ufshcd_hold/release sequences are met, it is possible that
scsi_block_reqs_cnt is increased twice but only one ungate work is
queued. To make sure scsi_block_reqs_cnt is handled by ufshcd_hold() and
ufshcd_ungate_work() in a paired way, increase it only if queue_work()
returns true.

Change-Id: I35f870e49cc832bb6f4b58763e3240f05b98ec13
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Ziqi Chen <ziqichen@codeaurora.org>
Signed-off-by: Alexander Winkowski <dereference23@outlook.com>

drivers/scsi/ufs/ufshcd.c

@@ -2679,12 +2679,12 @@ start:
 		 * work and to enable clocks.
 		 */
 	case CLKS_OFF:
-		__ufshcd_scsi_block_requests(hba);
 		hba->clk_gating.state = REQ_CLKS_ON;
 		trace_ufshcd_clk_gating(dev_name(hba->dev),
 					hba->clk_gating.state);
-		queue_work(hba->clk_gating.clk_gating_workq,
-				&hba->clk_gating.ungate_work);
+		if (queue_work(hba->clk_gating.clk_gating_workq,
+				&hba->clk_gating.ungate_work))
+			__ufshcd_scsi_block_requests(hba);
 		/*
 		 * fall through to check if we should wait for this
 		 * work to be done or not.