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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Pi-Hsun Shih <pihsun@chromium.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>
Subject: [PATCH 5.5 23/65] platform/chrome: cros_ec_rpmsg: Fix race with host event
Date:   Mon, 20 Apr 2020 14:38:27 +0200
Message-Id: <20200420121511.525317370@linuxfoundation.org>
In-Reply-To: <20200420121505.909671922@linuxfoundation.org>
References: <20200420121505.909671922@linuxfoundation.org>
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From: Pi-Hsun Shih <pihsun@chromium.org>

commit f775ac78fcfc6bdc96bdda07029d11f2a5e84869 upstream.

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>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/platform/chrome/cros_ec_rpmsg.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/platform/chrome/cros_ec_rpmsg.c
+++ b/drivers/platform/chrome/cros_ec_rpmsg.c
@@ -42,6 +42,8 @@ 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;
 };
 
 /**
@@ -175,7 +177,14 @@ static int cros_ec_rpmsg_callback(struct
 		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);
@@ -238,6 +247,11 @@ static int cros_ec_rpmsg_probe(struct rp
 		return ret;
 	}
 
+	ec_rpmsg->probe_done = true;
+
+	if (ec_rpmsg->has_pending_host_event)
+		schedule_work(&ec_rpmsg->host_event_work);
+
 	return 0;
 }