linux-kernel - [PATCH 17/30] habanalabs: there is no kernel TDR in future ASICs

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Date:   Sat, 22 Jan 2022 21:57:18 +0200
From:   Oded Gabbay <ogabbay@...nel.org>
To:     linux-kernel@...r.kernel.org
Subject: [PATCH 17/30] habanalabs: there is no kernel TDR in future ASICs

In future ASICs, there is no kernel TDR for new workloads that are
submitted directly from user-space to the device.

Therefore, the driver can NEVER know that a workload has timed-out.

So, when the user asks us to wait for interrupt on the workload's
completion, and the wait has timed-out, it doesn't mean the workload
has timed-out. It only means the wait has timed-out, which is NOT an
error from driver's perspective.

Signed-off-by: Oded Gabbay <ogabbay@...nel.org>
---
 .../misc/habanalabs/common/command_submission.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/habanalabs/common/command_submission.c b/drivers/misc/habanalabs/common/command_submission.c
index 96ec1fd3882a..0f41c283082c 100644
--- a/drivers/misc/habanalabs/common/command_submission.c
+++ b/drivers/misc/habanalabs/common/command_submission.c
@@ -2941,11 +2941,14 @@ static int _hl_interrupt_wait_ioctl(struct hl_device *hdev, struct hl_ctx *ctx,
 				rc = -EIO;
 				*status = HL_WAIT_CS_STATUS_ABORTED;
 			} else {
-				dev_err_ratelimited(hdev->dev, "Waiting for interrupt ID %d timedout\n",
-						interrupt->interrupt_id);
-				rc = -ETIMEDOUT;
+				/* The wait has timed-out. We don't know anything beyond that
+				 * because the workload wasn't submitted through the driver.
+				 * Therefore, from driver's perspective, the workload is still
+				 * executing.
+				 */
+				rc = 0;
+				*status = HL_WAIT_CS_STATUS_BUSY;
 			}
-			*status = HL_WAIT_CS_STATUS_BUSY;
 		}
 	}
 
@@ -3058,6 +3061,12 @@ static int _hl_interrupt_wait_ioctl_user_addr(struct hl_device *hdev, struct hl_
 			interrupt->interrupt_id);
 		rc = -EINTR;
 	} else {
+		/* The wait has timed-out. We don't know anything beyond that
+		 * because the workload wasn't submitted through the driver.
+		 * Therefore, from driver's perspective, the workload is still
+		 * executing.
+		 */
+		rc = 0;
 		*status = HL_WAIT_CS_STATUS_BUSY;
 	}
 
-- 
2.25.1