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    Subject[PATCH v6 35/37] firmware: arm_scmi: make notify_priv really private
    Date
    Notification private data is currently accessible via handle->notify_priv;
    this data was indeed meant to be private to the notification core support
    and not to be accessible by SCMI drivers: make it private hiding it inside
    instance descriptor struct scmi_info and accessible only via dedicated
    helpers.

    Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
    ---
    drivers/firmware/arm_scmi/common.h | 4 +++
    drivers/firmware/arm_scmi/driver.c | 21 ++++++++++++++
    drivers/firmware/arm_scmi/notify.c | 45 ++++++++++--------------------
    include/linux/scmi_protocol.h | 3 --
    4 files changed, 40 insertions(+), 33 deletions(-)

    diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
    index 65db0aefc489..5fb64182610a 100644
    --- a/drivers/firmware/arm_scmi/common.h
    +++ b/drivers/firmware/arm_scmi/common.h
    @@ -341,4 +341,8 @@ void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem);
    bool shmem_poll_done(struct scmi_shared_mem __iomem *shmem,
    struct scmi_xfer *xfer);

    +void scmi_set_notification_instance_data(const struct scmi_handle *handle,
    + void *priv);
    +void *scmi_get_notification_instance_data(const struct scmi_handle *handle);
    +
    #endif /* _SCMI_COMMON_H */
    diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
    index 0a544463d0a2..159d3fa2b9b6 100644
    --- a/drivers/firmware/arm_scmi/driver.c
    +++ b/drivers/firmware/arm_scmi/driver.c
    @@ -113,6 +113,7 @@ struct scmi_protocol_instance {
    * @protocols_mtx: A mutex to protect protocols instances initialization.
    * @protocols_imp: List of protocols implemented, currently maximum of
    * MAX_PROTOCOLS_IMP elements allocated by the base protocol
    + * @notify_priv: Pointer to private data structure specific to notifications.
    * @node: List head
    * @users: Number of users of this instance
    */
    @@ -129,6 +130,7 @@ struct scmi_info {
    /* Ensure mutual exclusive access to protocols instance array */
    struct mutex protocols_mtx;
    u8 *protocols_imp;
    + void *notify_priv;
    struct list_head node;
    int users;
    };
    @@ -170,6 +172,25 @@ static inline void scmi_dump_header_dbg(struct device *dev,
    hdr->id, hdr->seq, hdr->protocol_id);
    }

    +void scmi_set_notification_instance_data(const struct scmi_handle *handle,
    + void *priv)
    +{
    + struct scmi_info *info = handle_to_scmi_info(handle);
    +
    + info->notify_priv = priv;
    + /* Ensure updated protocol private date are visible */
    + smp_wmb();
    +}
    +
    +void *scmi_get_notification_instance_data(const struct scmi_handle *handle)
    +{
    + struct scmi_info *info = handle_to_scmi_info(handle);
    +
    + /* Ensure protocols_private_data has been updated */
    + smp_rmb();
    + return info->notify_priv;
    +}
    +
    /**
    * scmi_xfer_get() - Allocate one message
    *
    diff --git a/drivers/firmware/arm_scmi/notify.c b/drivers/firmware/arm_scmi/notify.c
    index d88bc9960c7c..39374255b3a7 100644
    --- a/drivers/firmware/arm_scmi/notify.c
    +++ b/drivers/firmware/arm_scmi/notify.c
    @@ -582,11 +582,9 @@ int scmi_notify(const struct scmi_handle *handle, u8 proto_id, u8 evt_id,
    struct scmi_event_header eh;
    struct scmi_notify_instance *ni;

    - /* Ensure notify_priv is updated */
    - smp_rmb();
    - if (!handle->notify_priv)
    + ni = scmi_get_notification_instance_data(handle);
    + if (!ni)
    return 0;
    - ni = handle->notify_priv;

    r_evt = SCMI_GET_REVT(ni, proto_id, evt_id);
    if (!r_evt)
    @@ -762,11 +760,9 @@ int scmi_register_protocol_events(const struct scmi_handle *handle, u8 proto_id,
    (!ee->num_sources && !ee->ops->get_num_sources))
    return -EINVAL;

    - /* Ensure notify_priv is updated */
    - smp_rmb();
    - if (!handle->notify_priv)
    + ni = scmi_get_notification_instance_data(handle);
    + if (!ni)
    return -ENOMEM;
    - ni = handle->notify_priv;

    /* num_sources cannot be <= 0 */
    if (ee->num_sources) {
    @@ -851,12 +847,10 @@ void scmi_deregister_protocol_events(const struct scmi_handle *handle,
    struct scmi_notify_instance *ni;
    struct scmi_registered_events_desc *pd;

    - /* Ensure notify_priv is updated */
    - smp_rmb();
    - if (!handle->notify_priv)
    + ni = scmi_get_notification_instance_data(handle);
    + if (!ni)
    return;

    - ni = handle->notify_priv;
    pd = ni->registered_protocols[proto_id];
    if (!pd)
    return;
    @@ -1359,11 +1353,9 @@ static int scmi_register_notifier(const struct scmi_handle *handle,
    struct scmi_event_handler *hndl;
    struct scmi_notify_instance *ni;

    - /* Ensure notify_priv is updated */
    - smp_rmb();
    - if (!handle->notify_priv)
    + ni = scmi_get_notification_instance_data(handle);
    + if (!ni)
    return -ENODEV;
    - ni = handle->notify_priv;

    evt_key = MAKE_HASH_KEY(proto_id, evt_id,
    src_id ? *src_id : SRC_ID_MASK);
    @@ -1407,11 +1399,9 @@ static int scmi_unregister_notifier(const struct scmi_handle *handle,
    struct scmi_event_handler *hndl;
    struct scmi_notify_instance *ni;

    - /* Ensure notify_priv is updated */
    - smp_rmb();
    - if (!handle->notify_priv)
    + ni = scmi_get_notification_instance_data(handle);
    + if (!ni)
    return -ENODEV;
    - ni = handle->notify_priv;

    evt_key = MAKE_HASH_KEY(proto_id, evt_id,
    src_id ? *src_id : SRC_ID_MASK);
    @@ -1684,8 +1674,8 @@ int scmi_notification_init(struct scmi_handle *handle)

    INIT_WORK(&ni->init_work, scmi_protocols_late_init);

    + scmi_set_notification_instance_data(handle, ni);
    handle->notify_ops = &notify_ops;
    - handle->notify_priv = ni;
    /* Ensure handle is up to date */
    smp_wmb();

    @@ -1697,7 +1687,7 @@ int scmi_notification_init(struct scmi_handle *handle)

    err:
    dev_warn(handle->dev, "Initialization Failed.\n");
    - devres_release_group(handle->dev, NULL);
    + devres_release_group(handle->dev, gid);
    return -ENOMEM;
    }

    @@ -1709,15 +1699,10 @@ void scmi_notification_exit(struct scmi_handle *handle)
    {
    struct scmi_notify_instance *ni;

    - /* Ensure notify_priv is updated */
    - smp_rmb();
    - if (!handle->notify_priv)
    + ni = scmi_get_notification_instance_data(handle);
    + if (!ni)
    return;
    - ni = handle->notify_priv;
    -
    - handle->notify_priv = NULL;
    - /* Ensure handle is up to date */
    - smp_wmb();
    + scmi_set_notification_instance_data(handle, NULL);

    /* Destroy while letting pending work complete */
    destroy_workqueue(ni->notify_wq);
    diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
    index 58008b294e3b..51ec4dc4fd6a 100644
    --- a/include/linux/scmi_protocol.h
    +++ b/include/linux/scmi_protocol.h
    @@ -612,8 +612,6 @@ struct scmi_notify_ops {
    * @devm_put_protocol: devres managed method to release a protocol acquired
    * with devm_acquire/get_protocol
    * @notify_ops: pointer to set of notifications related operations
    - * @notify_priv: pointer to private data structure specific to notifications
    - * (for internal use only)
    */
    struct scmi_handle {
    struct device *dev;
    @@ -627,7 +625,6 @@ struct scmi_handle {
    void (*devm_put_protocol)(struct scmi_device *sdev, u8 proto);

    const struct scmi_notify_ops *notify_ops;
    - void *notify_priv;
    };

    enum scmi_std_protocol {
    --
    2.17.1
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