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    Subject[PATCH 3/5] staging: vme: add functions for bridge module refcounting
    Date
    This patch adds functions that allow for reference counting
    bridge modules. The patch introduces the functions
    'vme_bridge_get()' and 'vme_bridge_put()'.

    The functions are automatically called during .probe and .remove
    for drivers.

    This patch is based on the changes introduced by Emilio G. Cota
    in the patch:

    https://lkml.org/lkml/2010/10/25/492

    Signed-off-by: Manohar Vanga <manohar.vanga@cern.ch>
    ---
    drivers/staging/vme/bridges/vme_ca91cx42.c | 2 +
    drivers/staging/vme/bridges/vme_tsi148.c | 2 +
    drivers/staging/vme/vme.c | 54 ++++++++++++++++++++++++++-
    drivers/staging/vme/vme.h | 1 -
    drivers/staging/vme/vme_bridge.h | 1 +
    5 files changed, 57 insertions(+), 3 deletions(-)

    diff --git a/drivers/staging/vme/bridges/vme_ca91cx42.c b/drivers/staging/vme/bridges/vme_ca91cx42.c
    index 0e4feac..b80cb12 100644
    --- a/drivers/staging/vme/bridges/vme_ca91cx42.c
    +++ b/drivers/staging/vme/bridges/vme_ca91cx42.c
    @@ -1673,6 +1673,8 @@ static int ca91cx42_probe(struct pci_dev *pdev, const struct pci_device_id *id)
    ca91cx42_bridge->parent = &pdev->dev;
    strcpy(ca91cx42_bridge->name, driver_name);

    + ca91cx42_bridge->owner = THIS_MODULE;
    +
    /* Setup IRQ */
    retval = ca91cx42_irq_init(ca91cx42_bridge);
    if (retval != 0) {
    diff --git a/drivers/staging/vme/bridges/vme_tsi148.c b/drivers/staging/vme/bridges/vme_tsi148.c
    index 6c1167c..b0b434a 100644
    --- a/drivers/staging/vme/bridges/vme_tsi148.c
    +++ b/drivers/staging/vme/bridges/vme_tsi148.c
    @@ -2312,6 +2312,8 @@ static int tsi148_probe(struct pci_dev *pdev, const struct pci_device_id *id)
    tsi148_bridge->parent = &pdev->dev;
    strcpy(tsi148_bridge->name, driver_name);

    + tsi148_bridge->owner = THIS_MODULE;
    +
    /* Setup IRQ */
    retval = tsi148_irq_init(tsi148_bridge);
    if (retval != 0) {
    diff --git a/drivers/staging/vme/vme.c b/drivers/staging/vme/vme.c
    index feb2d00..664eae0 100644
    --- a/drivers/staging/vme/vme.c
    +++ b/drivers/staging/vme/vme.c
    @@ -52,6 +52,48 @@ static struct vme_bridge *dev_to_bridge(struct device *dev)
    }

    /*
    + * Increments the reference count of a VME bridge.
    + *
    + * On success, it can be assumed that the bridge won't be removed until
    + * the corresponding call to vme_put_bridge(). This along with
    + * vme_bridge_put are automatically called and VME device drivers need
    + * not worry about using this.
    + */
    +int vme_bridge_get(unsigned int bus_id)
    +{
    + int ret = -1;
    + struct vme_bridge *bridge;
    +
    + mutex_lock(&vme_buses_lock);
    + list_for_each_entry(bridge, &vme_bus_list, bus_list) {
    + if (bridge->num == bus_id) {
    + if (!bridge->owner)
    + dev_warn(bridge->parent,
    + "bridge->owner not set\n");
    + else if (try_module_get(bridge->owner))
    + ret = 0;
    + break;
    + }
    + }
    + mutex_unlock(&vme_buses_lock);
    + return ret;
    +}
    +
    +/*
    + * Decrements the reference count of a bridge
    + *
    + * This function decrements the reference count of the module that controls
    + * the bridge. It must come after a call to vme_get_bridge().
    + */
    +void vme_bridge_put(struct vme_bridge *bridge)
    +{
    + if (!bridge->owner)
    + dev_warn(bridge->parent, "bridge->owner not set\n");
    + else
    + module_put(bridge->owner);
    +}
    +
    +/*
    * Find the bridge that the resource is associated with.
    */
    static struct vme_bridge *find_bridge(struct vme_resource *resource)
    @@ -1496,14 +1538,20 @@ static int vme_bus_probe(struct device *dev)
    {
    struct vme_bridge *bridge;
    struct vme_driver *driver;
    - int retval = -ENODEV;
    + int retval = 0;

    driver = dev_to_vme_driver(dev);
    bridge = dev_to_bridge(dev);

    + if (vme_bridge_get(bridge->num))
    + return -ENXIO;
    +
    if (driver->probe != NULL)
    retval = driver->probe(dev, bridge->num, vme_calc_slot(dev));

    + if (driver->probe && retval)
    + vme_bridge_put(bridge);
    +
    return retval;
    }

    @@ -1511,7 +1559,7 @@ static int vme_bus_remove(struct device *dev)
    {
    struct vme_bridge *bridge;
    struct vme_driver *driver;
    - int retval = -ENODEV;
    + int retval = 0;

    driver = dev_to_vme_driver(dev);
    bridge = dev_to_bridge(dev);
    @@ -1519,6 +1567,8 @@ static int vme_bus_remove(struct device *dev)
    if (driver->remove != NULL)
    retval = driver->remove(dev, bridge->num, vme_calc_slot(dev));

    + vme_bridge_put(bridge);
    +
    return retval;
    }

    diff --git a/drivers/staging/vme/vme.h b/drivers/staging/vme/vme.h
    index 4155d8c..eb00a5e 100644
    --- a/drivers/staging/vme/vme.h
    +++ b/drivers/staging/vme/vme.h
    @@ -165,6 +165,5 @@ int vme_slot_get(struct device *);
    int vme_register_driver(struct vme_driver *);
    void vme_unregister_driver(struct vme_driver *);

    -
    #endif /* _VME_H_ */

    diff --git a/drivers/staging/vme/vme_bridge.h b/drivers/staging/vme/vme_bridge.h
    index 8959670..ef751a4 100644
    --- a/drivers/staging/vme/vme_bridge.h
    +++ b/drivers/staging/vme/vme_bridge.h
    @@ -113,6 +113,7 @@ struct vme_bridge {
    struct device *parent; /* Parent device (eg. pdev->dev for PCI) */
    void *driver_priv; /* Private pointer for the bridge driver */
    struct list_head bus_list; /* list of VME buses */
    + struct module *owner; /* module that owns the bridge */

    struct device dev[VME_SLOTS_MAX]; /* Device registered with
    * device model on VME bus
    --
    1.7.4.1


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