scsi: ufs: core: 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 37f4a24c2469
("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.

Link: https://lore.kernel.org/r/[e-mail]
Fixes: 1235fc569e0b ("scsi: ufs: core: Fix task management request completion timeout")
Fixes: 69a6c269c097 ("scsi: ufs: Use blk_{get,put}_request() to allocate and free TMFs")
Cc: [e-mail]
Tested-by: Bart Van Assche <[e-mail]>
Reviewed-by: Bart Van Assche <[e-mail]>
Signed-off-by: Adrian Hunter <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/ufs/ufshcd.c

···
 	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
···
  */
 static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba)
 {
-	unsigned long flags;
-	struct request_queue *q = hba->tmf_queue;
-	struct ctm_info ci = {
-		.hba	 = hba,
-	};
+	unsigned long flags, pending, issued;
+	irqreturn_t ret = IRQ_NONE;
+	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);
-	blk_mq_tagset_busy_iter(q->tag_set, ufshcd_compl_tm, &ci);
+	issued = hba->outstanding_tasks & ~pending;
+	for_each_set_bit(tag, &issued, hba->nutmrs) {
+		struct request *req = hba->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;
 }
 
 /**
···
 	ufshcd_hold(hba, false);
 
 	spin_lock_irqsave(host->host_lock, flags);
-	blk_mq_start_request(req);
 
 	task_tag = req->tag;
+	hba->tmf_rqs[req->tag] = req;
 	treq->upiu_req.req_header.dword_0 |= cpu_to_be32(task_tag);
 
 	memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq));
···
 	}
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
+	hba->tmf_rqs[req->tag] = NULL;
 	__clear_bit(task_tag, &hba->outstanding_tasks);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
···
 	if (IS_ERR(hba->tmf_queue)) {
 		err = PTR_ERR(hba->tmf_queue);
 		goto free_tmf_tag_set;
+	}
+	hba->tmf_rqs = devm_kcalloc(hba->dev, hba->nutmrs,
+				    sizeof(*hba->tmf_rqs), GFP_KERNEL);
+	if (!hba->tmf_rqs) {
+		err = -ENOMEM;
+		goto free_tmf_queue;
 	}
 
 	/* Reset the attached device */

drivers/scsi/ufs/ufshcd.h

···
 
 	struct blk_mq_tag_set tmf_tag_set;
 	struct request_queue *tmf_queue;
+	struct request **tmf_rqs;
 
 	struct uic_command *active_uic_cmd;
 	struct mutex uic_cmd_mutex;