[PATCH v4] fpga: stratix10-soc: Fix SVC mailbox handling during reconfiguration

[tze.yee.ng@altera.com]

From: Tien Sung Ang <tien.sung.ang@altera.com>

Fix incorrect stratix10_svc_done() usage during FPGA reconfiguration.

Do not call stratix10_svc_done() at the end of write_init() on success, so
the SVC session remains active through write() and write_complete(). Call
stratix10_svc_done() on failure in write_init() and write() so the shared
SVC mailbox is released when reconfiguration aborts, allowing coexistence
with other SVC clients such as soc64-hwmon.

Fixes: e7eef1d7633a ("fpga: add intel stratix10 soc fpga manager driver")
Cc: stable@vger.kernel.org # 5.1+
Signed-off-by: Tien Sung Ang <tien.sung.ang@altera.com>
Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
---
Changes in v4:
- Restructure write_init() per review: return 0 on success, single
  init_error path for stratix10_svc_done().
- Do not assign wait_for_completion_timeout() result to ret; removes
  the need for ret = 0.
- Revert PTR_ERR(kbuf) to -ENOMEM change; keep PTR_ERR(kbuf).
---
 drivers/fpga/stratix10-soc.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/fpga/stratix10-soc.c b/drivers/fpga/stratix10-soc.c
index 0a295ccf1644..b8ec2e6f615f 100644
--- a/drivers/fpga/stratix10-soc.c
+++ b/drivers/fpga/stratix10-soc.c
@@ -195,20 +195,18 @@ static int s10_ops_write_init(struct fpga_manager *mgr,
 	ret = s10_svc_send_msg(priv, COMMAND_RECONFIG,
 			       &ctype, sizeof(ctype));
 	if (ret < 0)
-		goto init_done;
+		goto init_error;
 
-	ret = wait_for_completion_timeout(
-		&priv->status_return_completion, S10_RECONFIG_TIMEOUT);
-	if (!ret) {
+	if (!wait_for_completion_timeout(&priv->status_return_completion,
+					 S10_RECONFIG_TIMEOUT)) {
 		dev_err(dev, "timeout waiting for RECONFIG_REQUEST\n");
 		ret = -ETIMEDOUT;
-		goto init_done;
+		goto init_error;
 	}
 
-	ret = 0;
 	if (!test_and_clear_bit(SVC_STATUS_OK, &priv->status)) {
 		ret = -ETIMEDOUT;
-		goto init_done;
+		goto init_error;
 	}
 
 	/* Allocate buffers from the service layer's pool. */
@@ -217,14 +215,16 @@ static int s10_ops_write_init(struct fpga_manager *mgr,
 		if (IS_ERR(kbuf)) {
 			s10_free_buffers(mgr);
 			ret = PTR_ERR(kbuf);
-			goto init_done;
+			goto init_error;
 		}
 
 		priv->svc_bufs[i].buf = kbuf;
 		priv->svc_bufs[i].lock = 0;
 	}
 
-init_done:
+	return 0;
+
+init_error:
 	stratix10_svc_done(priv->chan);
 	return ret;
 }
@@ -342,6 +342,9 @@ static int s10_ops_write(struct fpga_manager *mgr, const char *buf,
 	if (!s10_free_buffers(mgr))
 		dev_err(dev, "%s not all buffers were freed\n", __func__);
 
+	if (ret < 0)
+		stratix10_svc_done(priv->chan);
+
 	return ret;
 }
 
-- 
2.43.7