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    Subject[PATCH 5.2 313/313] platform/chrome: cros_ec_rpmsg: Fix race with host command when probe failed
    Date
    From: Pi-Hsun Shih <pihsun@chromium.org>

    [ Upstream commit 71cddb7097e2b0feb855d7fd7d59afd12cbee4bb ]

    Since the rpmsg_endpoint is created before probe is called, it's
    possible that a host event is received during cros_ec_register, and
    there would be some pending work in the host_event_work workqueue while
    cros_ec_register is called.

    If cros_ec_register fails, when the leftover work in host_event_work
    run, the ec_dev from the drvdata of the rpdev could be already set to
    NULL, causing kernel crash when trying to run cros_ec_get_next_event.

    Fix this by creating the rpmsg_endpoint by ourself, and when
    cros_ec_register fails (or on remove), destroy the endpoint first (to
    make sure there's no more new calls to cros_ec_rpmsg_callback), and then
    cancel all works in the host_event_work workqueue.

    Cc: stable@vger.kernel.org
    Fixes: 2de89fd98958 ("platform/chrome: cros_ec: Add EC host command support using rpmsg")
    Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
    Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/platform/chrome/cros_ec_rpmsg.c | 32 +++++++++++++++++++++----
    1 file changed, 28 insertions(+), 4 deletions(-)

    diff --git a/drivers/platform/chrome/cros_ec_rpmsg.c b/drivers/platform/chrome/cros_ec_rpmsg.c
    index 5d3fb2abad1d6..bec19d4814aba 100644
    --- a/drivers/platform/chrome/cros_ec_rpmsg.c
    +++ b/drivers/platform/chrome/cros_ec_rpmsg.c
    @@ -41,6 +41,7 @@ struct cros_ec_rpmsg {
    struct rpmsg_device *rpdev;
    struct completion xfer_ack;
    struct work_struct host_event_work;
    + struct rpmsg_endpoint *ept;
    };

    /**
    @@ -72,7 +73,6 @@ static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
    struct cros_ec_command *ec_msg)
    {
    struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
    - struct rpmsg_device *rpdev = ec_rpmsg->rpdev;
    struct ec_host_response *response;
    unsigned long timeout;
    int len;
    @@ -85,7 +85,7 @@ static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
    dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);

    reinit_completion(&ec_rpmsg->xfer_ack);
    - ret = rpmsg_send(rpdev->ept, ec_dev->dout, len);
    + ret = rpmsg_send(ec_rpmsg->ept, ec_dev->dout, len);
    if (ret) {
    dev_err(ec_dev->dev, "rpmsg send failed\n");
    return ret;
    @@ -196,11 +196,24 @@ static int cros_ec_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
    return 0;
    }

    +static struct rpmsg_endpoint *
    +cros_ec_rpmsg_create_ept(struct rpmsg_device *rpdev)
    +{
    + struct rpmsg_channel_info chinfo = {};
    +
    + strscpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
    + chinfo.src = rpdev->src;
    + chinfo.dst = RPMSG_ADDR_ANY;
    +
    + return rpmsg_create_ept(rpdev, cros_ec_rpmsg_callback, NULL, chinfo);
    +}
    +
    static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
    {
    struct device *dev = &rpdev->dev;
    struct cros_ec_rpmsg *ec_rpmsg;
    struct cros_ec_device *ec_dev;
    + int ret;

    ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
    if (!ec_dev)
    @@ -225,7 +238,18 @@ static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
    INIT_WORK(&ec_rpmsg->host_event_work,
    cros_ec_rpmsg_host_event_function);

    - return cros_ec_register(ec_dev);
    + ec_rpmsg->ept = cros_ec_rpmsg_create_ept(rpdev);
    + if (!ec_rpmsg->ept)
    + return -ENOMEM;
    +
    + ret = cros_ec_register(ec_dev);
    + if (ret < 0) {
    + rpmsg_destroy_ept(ec_rpmsg->ept);
    + cancel_work_sync(&ec_rpmsg->host_event_work);
    + return ret;
    + }
    +
    + return 0;
    }

    static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
    @@ -233,6 +257,7 @@ static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
    struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
    struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;

    + rpmsg_destroy_ept(ec_rpmsg->ept);
    cancel_work_sync(&ec_rpmsg->host_event_work);
    }

    @@ -249,7 +274,6 @@ static struct rpmsg_driver cros_ec_driver_rpmsg = {
    },
    .probe = cros_ec_rpmsg_probe,
    .remove = cros_ec_rpmsg_remove,
    - .callback = cros_ec_rpmsg_callback,
    };

    module_rpmsg_driver(cros_ec_driver_rpmsg);
    --
    2.20.1


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