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    SubjectRe: [PATCH] mtd_blkdevs: Convert to use the kthread API
    On Thu, Apr 19, 2007 at 12:55:28AM -0600, Eric W. Biederman wrote:
    > From: Eric W. Biederman <ebiederm@xmission.com> - unquoted
    >
    > thread_run is used intead of kernel_thread, daemonize, and mucking
    > around blocking signals directly.

    This is the full conversion I sent to Dave in April 2006, but never got
    any feedback to:


    Signed-off-by: Christoph Hellwig <hch@lst.de>

    Index: linux-2.6/drivers/mtd/mtd_blkdevs.c
    ===================================================================
    --- linux-2.6.orig/drivers/mtd/mtd_blkdevs.c 2007-01-29 10:03:52.000000000 +0100
    +++ linux-2.6/drivers/mtd/mtd_blkdevs.c 2007-04-22 13:22:03.000000000 +0200
    @@ -20,6 +20,7 @@
    #include <linux/hdreg.h>
    #include <linux/init.h>
    #include <linux/mutex.h>
    +#include <linux/kthread.h>
    #include <asm/uaccess.h>

    static LIST_HEAD(blktrans_majors);
    @@ -28,9 +29,7 @@ extern struct mutex mtd_table_mutex;
    extern struct mtd_info *mtd_table[];

    struct mtd_blkcore_priv {
    - struct completion thread_dead;
    - int exiting;
    - wait_queue_head_t thread_wq;
    + struct task_struct *thread;
    struct request_queue *rq;
    spinlock_t queue_lock;
    };
    @@ -83,38 +82,19 @@ static int mtd_blktrans_thread(void *arg
    /* we might get involved when memory gets low, so use PF_MEMALLOC */
    current->flags |= PF_MEMALLOC | PF_NOFREEZE;

    - daemonize("%sd", tr->name);
    -
    - /* daemonize() doesn't do this for us since some kernel threads
    - actually want to deal with signals. We can't just call
    - exit_sighand() since that'll cause an oops when we finally
    - do exit. */
    - spin_lock_irq(&current->sighand->siglock);
    - sigfillset(&current->blocked);
    - recalc_sigpending();
    - spin_unlock_irq(&current->sighand->siglock);
    -
    spin_lock_irq(rq->queue_lock);
    -
    - while (!tr->blkcore_priv->exiting) {
    + while (!kthread_should_stop()) {
    struct request *req;
    struct mtd_blktrans_dev *dev;
    int res = 0;
    - DECLARE_WAITQUEUE(wait, current);

    req = elv_next_request(rq);

    if (!req) {
    - add_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
    - set_current_state(TASK_INTERRUPTIBLE);
    -
    spin_unlock_irq(rq->queue_lock);
    -
    + set_current_state(TASK_INTERRUPTIBLE);
    schedule();
    - remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
    -
    spin_lock_irq(rq->queue_lock);
    -
    continue;
    }

    @@ -133,13 +113,13 @@ static int mtd_blktrans_thread(void *arg
    }
    spin_unlock_irq(rq->queue_lock);

    - complete_and_exit(&tr->blkcore_priv->thread_dead, 0);
    + return 0;
    }

    static void mtd_blktrans_request(struct request_queue *rq)
    {
    struct mtd_blktrans_ops *tr = rq->queuedata;
    - wake_up(&tr->blkcore_priv->thread_wq);
    + wake_up_process(tr->blkcore_priv->thread);
    }


    @@ -388,8 +368,6 @@ int register_mtd_blktrans(struct mtd_blk
    return ret;
    }
    spin_lock_init(&tr->blkcore_priv->queue_lock);
    - init_completion(&tr->blkcore_priv->thread_dead);
    - init_waitqueue_head(&tr->blkcore_priv->thread_wq);

    tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
    if (!tr->blkcore_priv->rq) {
    @@ -403,13 +381,14 @@ int register_mtd_blktrans(struct mtd_blk
    blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
    tr->blkshift = ffs(tr->blksize) - 1;

    - ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL);
    - if (ret < 0) {
    + tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
    + "%sd", tr->name);
    + if (IS_ERR(tr->blkcore_priv->thread)) {
    blk_cleanup_queue(tr->blkcore_priv->rq);
    unregister_blkdev(tr->major, tr->name);
    kfree(tr->blkcore_priv);
    mutex_unlock(&mtd_table_mutex);
    - return ret;
    + return PTR_ERR(tr->blkcore_priv->thread);
    }

    INIT_LIST_HEAD(&tr->devs);
    @@ -432,9 +411,7 @@ int deregister_mtd_blktrans(struct mtd_b
    mutex_lock(&mtd_table_mutex);

    /* Clean up the kernel thread */
    - tr->blkcore_priv->exiting = 1;
    - wake_up(&tr->blkcore_priv->thread_wq);
    - wait_for_completion(&tr->blkcore_priv->thread_dead);
    + kthread_stop(tr->blkcore_priv->thread);

    /* Remove it from the list of active majors */
    list_del(&tr->list);
    -
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