Commit 6c997918 authored by Serge E. Hallyn's avatar Serge E. Hallyn Committed by Linus Torvalds
Browse files

[PATCH] kthread: convert loop.c to kthread 



Convert loop.c from the deprecated kernel_thread to kthread.  This patch
simplifies the code quite a bit and passes similar testing to the previous
submission on both emulated x86 and s390.

Changes since last submission:
	switched to using a rather simple loop based on
	wait_event_interruptible.

Signed-off-by: default avatarSerge E. Hallyn <serue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 5b217fa7

drivers/block/loop.c

+24 −45
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ 
#include <linux/completion.h>

#include <linux/highmem.h>

#include <linux/gfp.h>

#include <linux/kthread.h>



#include <asm/uaccess.h>
@@ -522,15 +523,12 @@ static int loop_make_request(request_queue_t *q, struct bio *old_bio) 
		goto out;

	if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))

		goto out;

	lo->lo_pending++;

	loop_add_bio(lo, old_bio);

	wake_up(&lo->lo_event);

	spin_unlock_irq(&lo->lo_lock);

	complete(&lo->lo_bh_done);

	return 0;



out:

	if (lo->lo_pending == 0)

		complete(&lo->lo_bh_done);

	spin_unlock_irq(&lo->lo_lock);

	bio_io_error(old_bio, old_bio->bi_size);

	return 0;
@@ -570,14 +568,18 @@ static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio) 
 * to avoid blocking in our make_request_fn. it also does loop decrypting

 * on reads for block backed loop, as that is too heavy to do from

 * b_end_io context where irqs may be disabled.

 *

 * Loop explanation:  loop_clr_fd() sets lo_state to Lo_rundown before

 * calling kthread_stop().  Therefore once kthread_should_stop() is

 * true, make_request will not place any more requests.  Therefore

 * once kthread_should_stop() is true and lo_bio is NULL, we are

 * done with the loop.

 */

static int loop_thread(void *data)

{

	struct loop_device *lo = data;

	struct bio *bio;



	daemonize("loop%d", lo->lo_number);



	/*

	 * loop can be used in an encrypted device,

	 * hence, it mustn't be stopped at all
@@ -587,47 +589,21 @@ static int loop_thread(void *data) 


	set_user_nice(current, -20);



	lo->lo_state = Lo_bound;

	lo->lo_pending = 1;



	/*

	 * complete it, we are running

	 */

	complete(&lo->lo_done);

	while (!kthread_should_stop() || lo->lo_bio) {



	for (;;) {

		int pending;

		wait_event_interruptible(lo->lo_event,

				lo->lo_bio || kthread_should_stop());



		if (wait_for_completion_interruptible(&lo->lo_bh_done))

		if (!lo->lo_bio)

			continue;



		spin_lock_irq(&lo->lo_lock);



		/*

		 * could be completed because of tear-down, not pending work

		 */

		if (unlikely(!lo->lo_pending)) {

			spin_unlock_irq(&lo->lo_lock);

			break;

		}



		bio = loop_get_bio(lo);

		lo->lo_pending--;

		pending = lo->lo_pending;

		spin_unlock_irq(&lo->lo_lock);



		BUG_ON(!bio);

		loop_handle_bio(lo, bio);



		/*

		 * upped both for pending work and tear-down, lo_pending

		 * will hit zero then

		 */

		if (unlikely(!pending))

			break;

	}



	complete(&lo->lo_done);

	return 0;

}
@@ -840,10 +816,15 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file, 


	set_blocksize(bdev, lo_blocksize);



	error = kernel_thread(loop_thread, lo, CLONE_KERNEL);

	if (error < 0)

	lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",

						lo->lo_number);

	if (IS_ERR(lo->lo_thread)) {

		error = PTR_ERR(lo->lo_thread);

		lo->lo_thread = NULL;

		goto out_putf;

	wait_for_completion(&lo->lo_done);

	}

	lo->lo_state = Lo_bound;

	wake_up_process(lo->lo_thread);

	return 0;



 out_putf:
@@ -907,12 +888,9 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) 


	spin_lock_irq(&lo->lo_lock);

	lo->lo_state = Lo_rundown;

	lo->lo_pending--;

	if (!lo->lo_pending)

		complete(&lo->lo_bh_done);

	spin_unlock_irq(&lo->lo_lock);



	wait_for_completion(&lo->lo_done);

	kthread_stop(lo->lo_thread);



	lo->lo_backing_file = NULL;
@@ -925,6 +903,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) 
	lo->lo_sizelimit = 0;

	lo->lo_encrypt_key_size = 0;

	lo->lo_flags = 0;

	lo->lo_thread = NULL;

	memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);

	memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);

	memset(lo->lo_file_name, 0, LO_NAME_SIZE);
@@ -1287,9 +1266,9 @@ static int __init loop_init(void) 
		if (!lo->lo_queue)

			goto out_mem4;

		mutex_init(&lo->lo_ctl_mutex);

		init_completion(&lo->lo_done);

		init_completion(&lo->lo_bh_done);

		lo->lo_number = i;

		lo->lo_thread = NULL;

		init_waitqueue_head(&lo->lo_event);

		spin_lock_init(&lo->lo_lock);

		disk->major = LOOP_MAJOR;

		disk->first_minor = i;

include/linux/loop.h

+2 −3
Original line number Diff line number Diff line
@@ -59,10 +59,9 @@ struct loop_device { 
	struct bio 		*lo_bio;

	struct bio		*lo_biotail;

	int			lo_state;

	struct completion	lo_done;

	struct completion	lo_bh_done;

	struct mutex		lo_ctl_mutex;

	int			lo_pending;

	struct task_struct	*lo_thread;

	wait_queue_head_t	lo_event;



	request_queue_t		*lo_queue;

};

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