FROMLIST: scsi: ufs: Fix task management completion

The UFS driver uses blk_mq_tagset_busy_iter() when identifying task
management requests to complete, however blk_mq_tagset_busy_iter()
doesn't work.

blk_mq_tagset_busy_iter() only iterates requests dispatched by the block
layer. That appears as if it might have started since commit 37f4a24c24
("blk-mq: centralise related handling into blk_mq_get_driver_tag") which
removed 'data->hctx->tags->rqs[rq->tag] = rq' from blk_mq_rq_ctx_init()
which gets called:

	blk_get_request
		blk_mq_alloc_request
			__blk_mq_alloc_request
				blk_mq_rq_ctx_init

Since UFS task management requests are not dispatched by the block
layer, hctx->tags->rqs[rq->tag] remains NULL,  and since
blk_mq_tagset_busy_iter() relies on finding requests using
hctx->tags->rqs[rq->tag], UFS task management requests are never found by
blk_mq_tagset_busy_iter().

By using blk_mq_tagset_busy_iter(), the UFS driver was relying on internal
details of the block layer, which was fragile and subsequently got
broken. Fix by removing the use of blk_mq_tagset_busy_iter() and having
the driver keep track of task management requests.

Fixes: 1235fc569e0bf5 ("scsi: ufs: core: Fix task management request completion timeout")
Fixes: 69a6c269c0 ("scsi: ufs: Use blk_{get,put}_request() to allocate and free TMFs")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Bug: 200291871
Link: https://lore.kernel.org/linux-scsi/20210922091059.4040-1-adrian.hunter@intel.com/
Change-Id: I4e11f40c7371fd66b3a6b570d06c956b113df142
Signed-off-by: Bart Van Assche <bvanassche@google.com>

drivers/scsi/ufs/ufshcd-add-info.h

@@ -11,6 +11,7 @@
  */
 struct ufs_hba_add_info {
 	struct ufs_hba hba;
+	struct request **tmf_rqs;
 #ifdef CONFIG_SCSI_UFS_HPB
 	struct ufshpb_dev_info hpb_dev;
 #endif

drivers/scsi/ufs/ufshcd.c

@@ -6364,27 +6364,6 @@ static irqreturn_t ufshcd_check_errors(struct ufs_hba *hba, u32 intr_status)
 	return retval;
 }
 
-struct ctm_info {
-	struct ufs_hba	*hba;
-	unsigned long	pending;
-	unsigned int	ncpl;
-};
-
-static bool ufshcd_compl_tm(struct request *req, void *priv, bool reserved)
-{
-	struct ctm_info *const ci = priv;
-	struct completion *c;
-
-	WARN_ON_ONCE(reserved);
-	if (test_bit(req->tag, &ci->pending))
-		return true;
-	ci->ncpl++;
-	c = req->end_io_data;
-	if (c)
-		complete(c);
-	return true;
-}
-
 /**
  * ufshcd_tmc_handler - handle task management function completion
  * @hba: per adapter instance
@@ -6395,18 +6374,25 @@ static bool ufshcd_compl_tm(struct request *req, void *priv, bool reserved)
  */
 static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba)
 {
-	unsigned long flags;
+	struct request **tmf_rqs = ufs_hba_add_info(hba)->tmf_rqs;
-	struct request_queue *q = hba->tmf_queue;
+	unsigned long flags, pending, issued;
-	struct ctm_info ci = {
+	irqreturn_t ret = IRQ_NONE;
-		.hba	 = hba,
+	int tag;
-	};
+
+	pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
-	ci.pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
+	issued = hba->outstanding_tasks & ~pending;
-	blk_mq_tagset_busy_iter(q->tag_set, ufshcd_compl_tm, &ci);
+	for_each_set_bit(tag, &issued, hba->nutmrs) {
+		struct request *req = tmf_rqs[tag];
+		struct completion *c = req->end_io_data;
+
+		complete(c);
+		ret = IRQ_HANDLED;
+	}
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
-	return ci.ncpl ? IRQ_HANDLED : IRQ_NONE;
+	return ret;
 }
 
 /**
@@ -6511,6 +6497,7 @@ out:
 static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba,
 		struct utp_task_req_desc *treq, u8 tm_function)
 {
+	struct request **tmf_rqs = ufs_hba_add_info(hba)->tmf_rqs;
 	struct request_queue *q = hba->tmf_queue;
 	struct Scsi_Host *host = hba->host;
 	DECLARE_COMPLETION_ONSTACK(wait);
@@ -6529,9 +6516,9 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba,
 	ufshcd_hold(hba, false);
 
 	spin_lock_irqsave(host->host_lock, flags);
-	blk_mq_start_request(req);
 
 	task_tag = req->tag;
+	tmf_rqs[req->tag] = req;
 	treq->req_header.dword_0 |= cpu_to_be32(task_tag);
 
 	memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq));
@@ -6575,6 +6562,7 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba,
 	}
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
+	tmf_rqs[req->tag] = NULL;
 	__clear_bit(task_tag, &hba->outstanding_tasks);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
@@ -9367,6 +9355,7 @@ static const struct blk_mq_ops ufshcd_tmf_ops = {
  */
 int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 {
+	struct request ***tmf_rqs = &ufs_hba_add_info(hba)->tmf_rqs;
 	int err;
 	struct Scsi_Host *host = hba->host;
 	struct device *dev = hba->dev;
@@ -9504,6 +9493,12 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 		err = PTR_ERR(hba->tmf_queue);
 		goto free_tmf_tag_set;
 	}
+	*tmf_rqs = devm_kcalloc(hba->dev, hba->nutmrs, sizeof(**tmf_rqs),
+				GFP_KERNEL);
+	if (!*tmf_rqs) {
+		err = -ENOMEM;
+		goto free_tmf_queue;
+	}
 
 	/* Reset the attached device */
 	ufshcd_vops_device_reset(hba);

drivers/scsi/ufs/ufshcd.h

@@ -843,6 +843,12 @@ struct ufs_hba {
 
 	struct blk_mq_tag_set tmf_tag_set;
 	struct request_queue *tmf_queue;
+#if 0
+	/*
+	 * This has been moved into struct ufs_hba_add_info because of the GKI.
+	 */
+	struct request **tmf_rqs;
+#endif
 
 	struct uic_command *active_uic_cmd;
 	struct mutex uic_cmd_mutex;