linux-kernel - [PATCH 05/15] habanalabs: avoid divide by zero in device utilization

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Message-Id: <20221027091007.664797-5-ogabbay@kernel.org>
Date:   Thu, 27 Oct 2022 12:09:57 +0300
From:   Oded Gabbay <ogabbay@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ohad Sharabi <osharabi@...ana.ai>
Subject: [PATCH 05/15] habanalabs: avoid divide by zero in device utilization

From: Ohad Sharabi <osharabi@...ana.ai>

Currently there is no verification whether the divisor is legal.

Signed-off-by: Ohad Sharabi <osharabi@...ana.ai>
Reviewed-by: Oded Gabbay <ogabbay@...nel.org>
Signed-off-by: Oded Gabbay <ogabbay@...nel.org>
---
 drivers/misc/habanalabs/common/device.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/habanalabs/common/device.c b/drivers/misc/habanalabs/common/device.c
index 0e88396744a1..b71303ba11d0 100644
--- a/drivers/misc/habanalabs/common/device.c
+++ b/drivers/misc/habanalabs/common/device.c
@@ -987,11 +987,16 @@ static void device_late_fini(struct hl_device *hdev)
 
 int hl_device_utilization(struct hl_device *hdev, u32 *utilization)
 {
-	u64 max_power, curr_power, dc_power, dividend;
+	u64 max_power, curr_power, dc_power, dividend, divisor;
 	int rc;
 
 	max_power = hdev->max_power;
 	dc_power = hdev->asic_prop.dc_power_default;
+	divisor = max_power - dc_power;
+	if (!divisor) {
+		dev_warn(hdev->dev, "device utilization is not supported\n");
+		return -EOPNOTSUPP;
+	}
 	rc = hl_fw_cpucp_power_get(hdev, &curr_power);
 
 	if (rc)
@@ -1000,7 +1005,7 @@ int hl_device_utilization(struct hl_device *hdev, u32 *utilization)
 	curr_power = clamp(curr_power, dc_power, max_power);
 
 	dividend = (curr_power - dc_power) * 100;
-	*utilization = (u32) div_u64(dividend, (max_power - dc_power));
+	*utilization = (u32) div_u64(dividend, divisor);
 
 	return 0;
 }
-- 
2.25.1