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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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