[PATCH v2 3/3] iommu/riscv: Avoid waiting on failed command enqueue

[fangyu.yu@linux.alibaba.com]

From: Fangyu Yu <fangyu.yu@linux.alibaba.com>

Do not wait for IOFENCE.C completion when the command failed to enter the
queue. The command was not published to hardware, so waiting for its
producer index can only report a misleading execution timeout.

Fixes: 856c0cfe5c5f ("iommu/riscv: Command and fault queue support")
Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
---
 drivers/iommu/riscv/iommu.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index e335beb70e42..fe8e6d0f8a23 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -419,8 +419,9 @@ static int riscv_iommu_queue_wait_for_space(struct riscv_iommu_queue *queue,
 }
 
 /* Enqueue an entry and publish it to the hardware queue. */
-static unsigned int riscv_iommu_queue_send(struct riscv_iommu_queue *queue,
-					   void *entry, size_t entry_size)
+static int riscv_iommu_queue_send(struct riscv_iommu_queue *queue,
+					  void *entry, size_t entry_size,
+					  unsigned int *out_prod)
 {
 	unsigned int prod;
 	unsigned int head;
@@ -462,14 +463,16 @@ static unsigned int riscv_iommu_queue_send(struct riscv_iommu_queue *queue,
 	atomic_set(&queue->tail, prod + 1);
 	atomic_set(&queue->prod, prod + 1);
 
-	raw_spin_unlock_irqrestore(&queue->lock, flags);
+	if (out_prod)
+		*out_prod = prod;
 
-	return prod;
+	raw_spin_unlock_irqrestore(&queue->lock, flags);
+	return 0;
 
 err_busy:
 	/* Report the failure and continue; full RAS recovery is not implemented. */
 	dev_err_once(queue->iommu->dev, "Hardware error: command enqueue failed\n");
-	return prod;
+	return ret;
 }
 
 /*
@@ -508,7 +511,7 @@ static irqreturn_t riscv_iommu_cmdq_process(int irq, void *data)
 static void riscv_iommu_cmd_send(struct riscv_iommu_device *iommu,
 				 struct riscv_iommu_command *cmd)
 {
-	riscv_iommu_queue_send(&iommu->cmdq, cmd, sizeof(*cmd));
+	riscv_iommu_queue_send(&iommu->cmdq, cmd, sizeof(*cmd), NULL);
 }
 
 /* Send IOFENCE.C command and wait for all scheduled commands to complete. */
@@ -517,9 +520,12 @@ static void riscv_iommu_cmd_sync(struct riscv_iommu_device *iommu,
 {
 	struct riscv_iommu_command cmd;
 	unsigned int prod;
+	int ret;
 
 	riscv_iommu_cmd_iofence(&cmd);
-	prod = riscv_iommu_queue_send(&iommu->cmdq, &cmd, sizeof(cmd));
+	ret = riscv_iommu_queue_send(&iommu->cmdq, &cmd, sizeof(cmd), &prod);
+	if (ret)
+		return;
 
 	if (!timeout_us)
 		return;
-- 
2.50.1