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[PATCH] kthread: convert loop.c to kthread

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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: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Serge E. Hallyn 2006-09-29 01:59:11 -07:00 committed by Linus Torvalds
parent 5b217fa75c
commit 6c9979185c
2 changed files with 26 additions and 48 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

69
drivers/block/loop.c
View file

@ -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;
while (!kthread_should_stop() || lo->lo_bio) {
/*
* complete it, we are running
*/
complete(&lo->lo_done);
wait_event_interruptible(lo->lo_event,
lo->lo_bio || kthread_should_stop());
for (;;) {
int pending;
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;

5
include/linux/loop.h
View file

@ -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;
};