linux-kernel - [PATCH 3/8] habanalabs: print context refcount value if hard reset fails

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Date:   Wed, 23 Nov 2022 16:57:56 +0200
From:   Oded Gabbay <ogabbay@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Tomer Tayar <ttayar@...ana.ai>
Subject: [PATCH 3/8] habanalabs: print context refcount value if hard reset fails

From: Tomer Tayar <ttayar@...ana.ai>

Failing to kill a user process during a hard reset can be due to a
reference to the user context which isn't released.
To make it easier to understand if this the reason for the failure and
not something else, add a print of the context refcount value.

Signed-off-by: Tomer Tayar <ttayar@...ana.ai>
Reviewed-by: Oded Gabbay <ogabbay@...nel.org>
Signed-off-by: Oded Gabbay <ogabbay@...nel.org>
---
 drivers/misc/habanalabs/common/device.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/habanalabs/common/device.c b/drivers/misc/habanalabs/common/device.c
index f5864893237c..926f230def56 100644
--- a/drivers/misc/habanalabs/common/device.c
+++ b/drivers/misc/habanalabs/common/device.c
@@ -696,10 +696,22 @@ static void device_hard_reset_pending(struct work_struct *work)
 	flags = device_reset_work->flags | HL_DRV_RESET_FROM_RESET_THR;
 
 	rc = hl_device_reset(hdev, flags);
+
 	if ((rc == -EBUSY) && !hdev->device_fini_pending) {
-		dev_info(hdev->dev,
-			"Could not reset device. will try again in %u seconds",
-			HL_PENDING_RESET_PER_SEC);
+		struct hl_ctx *ctx = hl_get_compute_ctx(hdev);
+
+		if (ctx) {
+			/* The read refcount value should subtracted by one, because the read is
+			 * protected with hl_get_compute_ctx().
+			 */
+			dev_info(hdev->dev,
+				"Could not reset device (compute_ctx refcount %u). will try again in %u seconds",
+				kref_read(&ctx->refcount) - 1, HL_PENDING_RESET_PER_SEC);
+			hl_ctx_put(ctx);
+		} else {
+			dev_info(hdev->dev, "Could not reset device. will try again in %u seconds",
+				HL_PENDING_RESET_PER_SEC);
+		}
 
 		queue_delayed_work(hdev->reset_wq, &device_reset_work->reset_work,
 					msecs_to_jiffies(HL_PENDING_RESET_PER_SEC * 1000));
-- 
2.25.1