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From:   Oded Gabbay <ogabbay@kernel.org>
To:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Cc:     farah kassabri <fkassabri@habana.ai>
Subject: [PATCH 2/3] accel/habanalabs: fix bug in decoder wait for cs completion
Date:   Thu, 28 Sep 2023 12:19:55 +0300
Message-Id: <20230928091956.47762-2-ogabbay@kernel.org>
In-Reply-To: <20230928091956.47762-1-ogabbay@kernel.org>
References: <20230928091956.47762-1-ogabbay@kernel.org>
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From: farah kassabri <fkassabri@habana.ai>

The decoder interrupts are handled in the interrupt context
same as all user interrupts.
In such case, the wait list should be protected by
spin_lock_irqsave in order to avoid deadlock that might happen
with the user submission flow.

Signed-off-by: farah kassabri <fkassabri@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
---
 .../accel/habanalabs/common/command_submission.c   | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/accel/habanalabs/common/command_submission.c b/drivers/accel/habanalabs/common/command_submission.c
index 4f7b70d9754c..3aa6eeef443b 100644
--- a/drivers/accel/habanalabs/common/command_submission.c
+++ b/drivers/accel/habanalabs/common/command_submission.c
@@ -3526,7 +3526,7 @@ static int _hl_interrupt_wait_ioctl_user_addr(struct hl_device *hdev, struct hl_
 				u64 *timestamp)
 {
 	struct hl_user_pending_interrupt *pend;
-	unsigned long timeout;
+	unsigned long timeout, flags;
 	u64 completion_value;
 	long completion_rc;
 	int rc = 0;
@@ -3546,9 +3546,9 @@ static int _hl_interrupt_wait_ioctl_user_addr(struct hl_device *hdev, struct hl_
 	/* Add pending user interrupt to relevant list for the interrupt
 	 * handler to monitor
 	 */
-	spin_lock(&interrupt->wait_list_lock);
+	spin_lock_irqsave(&interrupt->wait_list_lock, flags);
 	list_add_tail(&pend->list_node, &interrupt->wait_list_head);
-	spin_unlock(&interrupt->wait_list_lock);
+	spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
 
 	/* We check for completion value as interrupt could have been received
 	 * before we added the node to the wait list
@@ -3579,14 +3579,14 @@ static int _hl_interrupt_wait_ioctl_user_addr(struct hl_device *hdev, struct hl_
 	 * If comparison fails, keep waiting until timeout expires
 	 */
 	if (completion_rc > 0) {
-		spin_lock(&interrupt->wait_list_lock);
+		spin_lock_irqsave(&interrupt->wait_list_lock, flags);
 		/* reinit_completion must be called before we check for user
 		 * completion value, otherwise, if interrupt is received after
 		 * the comparison and before the next wait_for_completion,
 		 * we will reach timeout and fail
 		 */
 		reinit_completion(&pend->fence.completion);
-		spin_unlock(&interrupt->wait_list_lock);
+		spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
 
 		if (copy_from_user(&completion_value, u64_to_user_ptr(user_address), 8)) {
 			dev_err(hdev->dev, "Failed to copy completion value from user\n");
@@ -3623,9 +3623,9 @@ static int _hl_interrupt_wait_ioctl_user_addr(struct hl_device *hdev, struct hl_
 	}
 
 remove_pending_user_interrupt:
-	spin_lock(&interrupt->wait_list_lock);
+	spin_lock_irqsave(&interrupt->wait_list_lock, flags);
 	list_del(&pend->list_node);
-	spin_unlock(&interrupt->wait_list_lock);
+	spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
 
 	*timestamp = ktime_to_ns(pend->fence.timestamp);
 
-- 
2.34.1