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From:   Pi-Hsun Shih <pihsun@chromium.org>
Cc:     Pi-Hsun Shih <pihsun@chromium.org>,
        Benson Leung <bleung@chromium.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        Guenter Roeck <groeck@chromium.org>,
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] platform/chrome: cros_ec_rpmsg: Fix race with host event.
Date:   Fri, 14 Feb 2020 16:26:38 +0800
Message-Id: <20200214082638.92070-1-pihsun@chromium.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Host event can be sent by remoteproc by any time, and
cros_ec_rpmsg_callback would be called after cros_ec_rpmsg_create_ept.
But the cros_ec_device is initialized after that, which cause host event
handler to use cros_ec_device that are not initialized properly yet.

Fix this by don't schedule host event handler before cros_ec_register
returns. Instead, remember that we have a pending host event, and
schedule host event handler after cros_ec_register.

Fixes: 71cddb7097e2 ("platform/chrome: cros_ec_rpmsg: Fix race with host command when probe failed.")
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
---
 drivers/platform/chrome/cros_ec_rpmsg.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/chrome/cros_ec_rpmsg.c b/drivers/platform/chrome/cros_ec_rpmsg.c
index dbc3f5523b83..7e8629e3db74 100644
--- a/drivers/platform/chrome/cros_ec_rpmsg.c
+++ b/drivers/platform/chrome/cros_ec_rpmsg.c
@@ -44,6 +44,8 @@ struct cros_ec_rpmsg {
 	struct completion xfer_ack;
 	struct work_struct host_event_work;
 	struct rpmsg_endpoint *ept;
+	bool has_pending_host_event;
+	bool probe_done;
 };
 
 /**
@@ -177,7 +179,14 @@ static int cros_ec_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
 		memcpy(ec_dev->din, resp->data, len);
 		complete(&ec_rpmsg->xfer_ack);
 	} else if (resp->type == HOST_EVENT_MARK) {
-		schedule_work(&ec_rpmsg->host_event_work);
+		/*
+		 * If the host event is sent before cros_ec_register is
+		 * finished, queue the host event.
+		 */
+		if (ec_rpmsg->probe_done)
+			schedule_work(&ec_rpmsg->host_event_work);
+		else
+			ec_rpmsg->has_pending_host_event = true;
 	} else {
 		dev_warn(ec_dev->dev, "rpmsg received invalid type = %d",
 			 resp->type);
@@ -240,6 +249,11 @@ static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
 		return ret;
 	}
 
+	ec_rpmsg->probe_done = true;
+
+	if (ec_rpmsg->has_pending_host_event)
+		schedule_work(&ec_rpmsg->host_event_work);
+
 	return 0;
 }
 

base-commit: b19e8c68470385dd2c5440876591fddb02c8c402
-- 
2.25.0.265.gbab2e86ba0-goog