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    Subject[PATCH 2/2] remoteproc: remove the now-redundant kref
    Date
    Now that every rproc instance contains a device, we don't need a
    kref anymore to maintain the refcount of the rproc instances:
    that's what device are good with!

    This patch removes the now-redundant kref, and switches to
    {get, put}_device instead of kref_{get, put}.

    We also don't need the kref's release function anymore, and instead,
    we just utilize the class's release handler (which is now responsible
    for all memory de-allocations).

    Cc: Stephen Boyd <sboyd@codeaurora.org>
    Cc: Fernando Guzman Lugo <fernando.lugo@ti.com>
    Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
    ---
    drivers/remoteproc/remoteproc_core.c | 59 +++++++++++---------------------
    drivers/remoteproc/remoteproc_virtio.c | 8 ++--
    include/linux/remoteproc.h | 3 --
    3 files changed, 24 insertions(+), 46 deletions(-)

    diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
    index 9e3d4cf..7214393 100644
    --- a/drivers/remoteproc/remoteproc_core.c
    +++ b/drivers/remoteproc/remoteproc_core.c
    @@ -1269,42 +1269,12 @@ out:
    }
    EXPORT_SYMBOL(rproc_shutdown);

    -/**
    - * rproc_release() - completely deletes the existence of a remote processor
    - * @kref: the rproc's kref
    - *
    - * This function should _never_ be called directly.
    - *
    - * The only reasonable location to use it is as an argument when kref_put'ing
    - * @rproc's refcount.
    - *
    - * This way it will be called when no one holds a valid pointer to this @rproc
    - * anymore (and obviously after it is removed from the rprocs klist).
    - *
    - * Note: this function is not static because rproc_vdev_release() needs it when
    - * it decrements @rproc's refcount.
    - */
    -void rproc_release(struct kref *kref)
    -{
    - struct rproc *rproc = container_of(kref, struct rproc, refcount);
    -
    - dev_info(&rproc->dev, "removing %s\n", rproc->name);
    -
    - rproc_delete_debug_dir(rproc);
    -
    - /*
    - * At this point no one holds a reference to rproc anymore,
    - * so we can directly unroll rproc_alloc()
    - */
    - rproc_free(rproc);
    -}
    -
    /* will be called when an rproc is added to the rprocs klist */
    static void klist_rproc_get(struct klist_node *n)
    {
    struct rproc *rproc = container_of(n, struct rproc, node);

    - kref_get(&rproc->refcount);
    + get_device(&rproc->dev);
    }

    /* will be called when an rproc is removed from the rprocs klist */
    @@ -1312,7 +1282,7 @@ static void klist_rproc_put(struct klist_node *n)
    {
    struct rproc *rproc = container_of(n, struct rproc, node);

    - kref_put(&rproc->refcount, rproc_release);
    + put_device(&rproc->dev);
    }

    static struct rproc *next_rproc(struct klist_iter *i)
    @@ -1354,7 +1324,7 @@ struct rproc *rproc_get_by_name(const char *name)
    klist_iter_init(&rprocs, &i);
    while ((rproc = next_rproc(&i)) != NULL)
    if (!strcmp(rproc->name, name)) {
    - kref_get(&rproc->refcount);
    + get_device(&rproc->dev);
    break;
    }
    klist_iter_exit(&i);
    @@ -1367,7 +1337,7 @@ struct rproc *rproc_get_by_name(const char *name)

    ret = rproc_boot(rproc);
    if (ret < 0) {
    - kref_put(&rproc->refcount, rproc_release);
    + put_device(&rproc->dev);
    return NULL;
    }

    @@ -1394,7 +1364,7 @@ void rproc_put(struct rproc *rproc)
    rproc_shutdown(rproc);

    /* downref rproc's refcount */
    - kref_put(&rproc->refcount, rproc_release);
    + put_device(&rproc->dev);
    }
    EXPORT_SYMBOL(rproc_put);

    @@ -1462,10 +1432,23 @@ int rproc_register(struct rproc *rproc)
    }
    EXPORT_SYMBOL(rproc_register);

    +/**
    + * rproc_class_release() - release a remote processor instance
    + * @dev: the rproc's device
    + *
    + * This function should _never_ be called directly.
    + *
    + * It will be called by the driver core when no one holds a valid pointer
    + * to @dev anymore.
    + */
    static void rproc_class_release(struct device *dev)
    {
    struct rproc *rproc = container_of(dev, struct rproc, dev);

    + dev_info(&rproc->dev, "releasing %s\n", rproc->name);
    +
    + rproc_delete_debug_dir(rproc);
    +
    idr_remove_all(&rproc->notifyids);
    idr_destroy(&rproc->notifyids);

    @@ -1531,8 +1514,6 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,

    atomic_set(&rproc->power, 0);

    - kref_init(&rproc->refcount);
    -
    mutex_init(&rproc->lock);

    idr_init(&rproc->notifyids);
    @@ -1603,8 +1584,8 @@ int rproc_unregister(struct rproc *rproc)

    device_del(&rproc->dev);

    - /* the rproc will only be released after its refcount drops to zero */
    - kref_put(&rproc->refcount, rproc_release);
    + /* unroll rproc_alloc. TODO: we may want to let the users do that */
    + put_device(&rproc->dev);

    return 0;
    }
    diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
    index b662183..3541b44 100644
    --- a/drivers/remoteproc/remoteproc_virtio.c
    +++ b/drivers/remoteproc/remoteproc_virtio.c
    @@ -225,7 +225,7 @@ static struct virtio_config_ops rproc_virtio_config_ops = {

    /*
    * This function is called whenever vdev is released, and is responsible
    - * to decrement the remote processor's refcount taken when vdev was
    + * to decrement the remote processor's refcount which was taken when vdev was
    * added.
    *
    * Never call this function directly; it will be called by the driver
    @@ -240,7 +240,7 @@ static void rproc_vdev_release(struct device *dev)
    list_del(&rvdev->node);
    kfree(rvdev);

    - kref_put(&rproc->refcount, rproc_release);
    + put_device(&rproc->dev);
    }

    /**
    @@ -272,11 +272,11 @@ int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
    * Therefore we must increment the rproc refcount here, and decrement
    * it _only_ when the vdev is released.
    */
    - kref_get(&rproc->refcount);
    + get_device(&rproc->dev);

    ret = register_virtio_device(vdev);
    if (ret) {
    - kref_put(&rproc->refcount, rproc_release);
    + put_device(&rproc->dev);
    dev_err(dev, "failed to register vdev: %d\n", ret);
    goto out;
    }
    diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
    index 0b835d3..c6e46fa 100644
    --- a/include/linux/remoteproc.h
    +++ b/include/linux/remoteproc.h
    @@ -36,7 +36,6 @@
    #define REMOTEPROC_H

    #include <linux/types.h>
    -#include <linux/kref.h>
    #include <linux/klist.h>
    #include <linux/mutex.h>
    #include <linux/virtio.h>
    @@ -370,7 +369,6 @@ enum rproc_state {
    * @priv: private data which belongs to the platform-specific rproc module
    * @ops: platform-specific start/stop rproc handlers
    * @dev: underlying device
    - * @refcount: refcount of users that have a valid pointer to this rproc
    * @power: refcount of users who need this rproc powered up
    * @state: state of the device
    * @lock: lock which protects concurrent manipulations of the rproc
    @@ -393,7 +391,6 @@ struct rproc {
    void *priv;
    const struct rproc_ops *ops;
    struct device dev;
    - struct kref refcount;
    atomic_t power;
    unsigned int state;
    struct mutex lock;
    --
    1.7.5.4


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