1 files changed, 67 insertions, 31 deletions

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 452ad0612067..874490f7f5e7 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -734,17 +734,28 @@ static enum utp_ocs ufshcd_get_tr_ocs(struct ufshcd_lrb *lrbp)
 }
 
 /**
- * ufshcd_utrl_clear - Clear a bit in UTRLCLR register
+ * ufshcd_utrl_clear() - Clear requests from the controller request list.
  * @hba: per adapter instance
- * @pos: position of the bit to be cleared
+ * @mask: mask with one bit set for each request to be cleared
  */
-static inline void ufshcd_utrl_clear(struct ufs_hba *hba, u32 pos)
+static inline void ufshcd_utrl_clear(struct ufs_hba *hba, u32 mask)
 {
 	if (hba->quirks & UFSHCI_QUIRK_BROKEN_REQ_LIST_CLR)
-		ufshcd_writel(hba, (1 << pos), REG_UTP_TRANSFER_REQ_LIST_CLEAR);
-	else
-		ufshcd_writel(hba, ~(1 << pos),
-				REG_UTP_TRANSFER_REQ_LIST_CLEAR);
+		mask = ~mask;
+	/*
+	 * From the UFSHCI specification: "UTP Transfer Request List CLear
+	 * Register (UTRLCLR): This field is bit significant. Each bit
+	 * corresponds to a slot in the UTP Transfer Request List, where bit 0
+	 * corresponds to request slot 0. A bit in this field is set to ‘0’
+	 * by host software to indicate to the host controller that a transfer
+	 * request slot is cleared. The host controller
+	 * shall free up any resources associated to the request slot
+	 * immediately, and shall set the associated bit in UTRLDBR to ‘0’. The
+	 * host software indicates no change to request slots by setting the
+	 * associated bits in this field to ‘1’. Bits in this field shall only
+	 * be set ‘1’ or ‘0’ by host software when UTRLRSR is set to ‘1’."
+	 */
+	ufshcd_writel(hba, ~mask, REG_UTP_TRANSFER_REQ_LIST_CLEAR);
 }
 
 /**
@@ -2853,16 +2864,19 @@ static int ufshcd_compose_dev_cmd(struct ufs_hba *hba,
 	return ufshcd_compose_devman_upiu(hba, lrbp);
 }
 
-static int
-ufshcd_clear_cmd(struct ufs_hba *hba, int tag)
+/*
+ * Clear all the requests from the controller for which a bit has been set in
+ * @mask and wait until the controller confirms that these requests have been
+ * cleared.
+ */
+static int ufshcd_clear_cmds(struct ufs_hba *hba, u32 mask)
 {
 	int err = 0;
 	unsigned long flags;
-	u32 mask = 1 << tag;
 
 	/* clear outstanding transaction before retry */
 	spin_lock_irqsave(hba->host->host_lock, flags);
-	ufshcd_utrl_clear(hba, tag);
+	ufshcd_utrl_clear(hba, mask);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
 	/*
@@ -2933,37 +2947,59 @@ ufshcd_dev_cmd_completion(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
 static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba,
 		struct ufshcd_lrb *lrbp, int max_timeout)
 {
-	int err = 0;
-	unsigned long time_left;
+	unsigned long time_left = msecs_to_jiffies(max_timeout);
 	unsigned long flags;
+	bool pending;
+	int err;
 
+retry:
 	time_left = wait_for_completion_timeout(hba->dev_cmd.complete,
-			msecs_to_jiffies(max_timeout));
+						time_left);
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
-	hba->dev_cmd.complete = NULL;
 	if (likely(time_left)) {
+		/*
+		 * The completion handler called complete() and the caller of
+		 * this function still owns the @lrbp tag so the code below does
+		 * not trigger any race conditions.
+		 */
+		hba->dev_cmd.complete = NULL;
 		err = ufshcd_get_tr_ocs(lrbp);
 		if (!err)
 			err = ufshcd_dev_cmd_completion(hba, lrbp);
-	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
-
-	if (!time_left) {
+	} else {
 		err = -ETIMEDOUT;
 		dev_dbg(hba->dev, "%s: dev_cmd request timedout, tag %d\n",
 			__func__, lrbp->task_tag);
-		if (!ufshcd_clear_cmd(hba, lrbp->task_tag))
+		if (ufshcd_clear_cmds(hba, 1U << lrbp->task_tag) == 0) {
 			/* successfully cleared the command, retry if needed */
 			err = -EAGAIN;
-		/*
-		 * in case of an error, after clearing the doorbell,
-		 * we also need to clear the outstanding_request
-		 * field in hba
-		 */
-		spin_lock_irqsave(&hba->outstanding_lock, flags);
-		__clear_bit(lrbp->task_tag, &hba->outstanding_reqs);
-		spin_unlock_irqrestore(&hba->outstanding_lock, flags);
+			/*
+			 * Since clearing the command succeeded we also need to
+			 * clear the task tag bit from the outstanding_reqs
+			 * variable.
+			 */
+			spin_lock_irqsave(&hba->outstanding_lock, flags);
+			pending = test_bit(lrbp->task_tag,
+					   &hba->outstanding_reqs);
+			if (pending) {
+				hba->dev_cmd.complete = NULL;
+				__clear_bit(lrbp->task_tag,
+					    &hba->outstanding_reqs);
+			}
+			spin_unlock_irqrestore(&hba->outstanding_lock, flags);
+
+			if (!pending) {
+				/*
+				 * The completion handler ran while we tried to
+				 * clear the command.
+				 */
+				time_left = 1;
+				goto retry;
+			}
+		} else {
+			dev_err(hba->dev, "%s: failed to clear tag %d\n",
+				__func__, lrbp->task_tag);
+		}
 	}
 
 	return err;
@@ -6988,7 +7024,7 @@ static int ufshcd_eh_device_reset_handler(struct scsi_cmnd *cmd)
 	/* clear the commands that were pending for corresponding LUN */
 	for_each_set_bit(pos, &hba->outstanding_reqs, hba->nutrs) {
 		if (hba->lrb[pos].lun == lun) {
-			err = ufshcd_clear_cmd(hba, pos);
+			err = ufshcd_clear_cmds(hba, 1U << pos);
 			if (err)
 				break;
 			__ufshcd_transfer_req_compl(hba, 1U << pos);
@@ -7090,7 +7126,7 @@ static int ufshcd_try_to_abort_task(struct ufs_hba *hba, int tag)
 		goto out;
 	}
 
-	err = ufshcd_clear_cmd(hba, tag);
+	err = ufshcd_clear_cmds(hba, 1U << tag);
 	if (err)
 		dev_err(hba->dev, "%s: Failed clearing cmd at tag %d, err %d\n",
 			__func__, tag, err);