linux-kernel - [PATCH 23/26] habanalabs: fix handling of wait CS for interrupting signals

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Message-Id: <20221208151350.1833823-23-ogabbay@kernel.org>
Date:   Thu,  8 Dec 2022 17:13:47 +0200
From:   Oded Gabbay <ogabbay@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Tomer Tayar <ttayar@...ana.ai>
Subject: [PATCH 23/26] habanalabs: fix handling of wait CS for interrupting signals

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

The -ERESTARTSYS return value is not handled correctly when a signal is
received while waiting for CS completion.
This can lead to bad output values to user when waiting for a single CS
completion, and more severe, it can cause a non-stopping loop when
waiting to multi-CS completion and until a CS timeout.

Fix the handling and exit the waiting if this return value is received.

Signed-off-by: Tomer Tayar <ttayar@...ana.ai>
Reviewed-by: Oded Gabbay <ogabbay@...nel.org>
Signed-off-by: Oded Gabbay <ogabbay@...nel.org>
---
 .../misc/habanalabs/common/command_submission.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/misc/habanalabs/common/command_submission.c b/drivers/misc/habanalabs/common/command_submission.c
index cf3b82efc65c..0ec8cdcbb1f5 100644
--- a/drivers/misc/habanalabs/common/command_submission.c
+++ b/drivers/misc/habanalabs/common/command_submission.c
@@ -2590,7 +2590,9 @@ static int hl_wait_for_fence(struct hl_ctx *ctx, u64 seq, struct hl_fence *fence
 		*status = CS_WAIT_STATUS_BUSY;
 	}
 
-	if (error == -ETIMEDOUT || error == -EIO)
+	if (completion_rc == -ERESTARTSYS)
+		rc = completion_rc;
+	else if (error == -ETIMEDOUT || error == -EIO)
 		rc = error;
 
 	return rc;
@@ -2849,6 +2851,9 @@ static int hl_wait_multi_cs_completion(struct multi_cs_data *mcs_data,
 	if (completion_rc > 0)
 		mcs_data->timestamp = mcs_compl->timestamp;
 
+	if (completion_rc == -ERESTARTSYS)
+		return completion_rc;
+
 	mcs_data->wait_status = completion_rc;
 
 	return 0;
@@ -2994,15 +2999,15 @@ static int hl_multi_cs_wait_ioctl(struct hl_fpriv *hpriv, void *data)
 free_seq_arr:
 	kfree(cs_seq_arr);
 
-	if (rc)
-		return rc;
-
-	if (mcs_data.wait_status == -ERESTARTSYS) {
+	if (rc == -ERESTARTSYS) {
 		dev_err_ratelimited(hdev->dev,
 				"user process got signal while waiting for Multi-CS\n");
-		return -EINTR;
+		rc = -EINTR;
 	}
 
+	if (rc)
+		return rc;
+
 	/* update output args */
 	memset(args, 0, sizeof(*args));
 
-- 
2.25.1