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[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: 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
Linus Torvalds
parent
5b217fa75c
commit
6c9979185c
@ -72,6 +72,7 @@
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#include <linux/completion.h>
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#include <linux/highmem.h>
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#include <linux/gfp.h>
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#include <linux/kthread.h>
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#include <asm/uaccess.h>
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@ -522,15 +523,12 @@ static int loop_make_request(request_queue_t *q, struct bio *old_bio)
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goto out;
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if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
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goto out;
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lo->lo_pending++;
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loop_add_bio(lo, old_bio);
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wake_up(&lo->lo_event);
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spin_unlock_irq(&lo->lo_lock);
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complete(&lo->lo_bh_done);
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return 0;
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out:
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if (lo->lo_pending == 0)
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complete(&lo->lo_bh_done);
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spin_unlock_irq(&lo->lo_lock);
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bio_io_error(old_bio, old_bio->bi_size);
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return 0;
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@ -570,14 +568,18 @@ static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
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* to avoid blocking in our make_request_fn. it also does loop decrypting
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* on reads for block backed loop, as that is too heavy to do from
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* b_end_io context where irqs may be disabled.
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*
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* Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
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* calling kthread_stop(). Therefore once kthread_should_stop() is
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* true, make_request will not place any more requests. Therefore
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* once kthread_should_stop() is true and lo_bio is NULL, we are
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* done with the loop.
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*/
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static int loop_thread(void *data)
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{
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struct loop_device *lo = data;
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struct bio *bio;
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daemonize("loop%d", lo->lo_number);
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/*
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* loop can be used in an encrypted device,
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* hence, it mustn't be stopped at all
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@ -587,47 +589,21 @@ static int loop_thread(void *data)
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set_user_nice(current, -20);
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lo->lo_state = Lo_bound;
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lo->lo_pending = 1;
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while (!kthread_should_stop() || lo->lo_bio) {
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/*
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* complete it, we are running
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*/
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complete(&lo->lo_done);
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wait_event_interruptible(lo->lo_event,
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lo->lo_bio || kthread_should_stop());
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for (;;) {
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int pending;
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if (wait_for_completion_interruptible(&lo->lo_bh_done))
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if (!lo->lo_bio)
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continue;
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spin_lock_irq(&lo->lo_lock);
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/*
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* could be completed because of tear-down, not pending work
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*/
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if (unlikely(!lo->lo_pending)) {
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spin_unlock_irq(&lo->lo_lock);
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break;
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}
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bio = loop_get_bio(lo);
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lo->lo_pending--;
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pending = lo->lo_pending;
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spin_unlock_irq(&lo->lo_lock);
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BUG_ON(!bio);
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loop_handle_bio(lo, bio);
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/*
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* upped both for pending work and tear-down, lo_pending
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* will hit zero then
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*/
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if (unlikely(!pending))
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break;
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}
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complete(&lo->lo_done);
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return 0;
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}
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@ -840,10 +816,15 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file,
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set_blocksize(bdev, lo_blocksize);
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error = kernel_thread(loop_thread, lo, CLONE_KERNEL);
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if (error < 0)
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lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
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lo->lo_number);
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if (IS_ERR(lo->lo_thread)) {
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error = PTR_ERR(lo->lo_thread);
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lo->lo_thread = NULL;
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goto out_putf;
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wait_for_completion(&lo->lo_done);
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}
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lo->lo_state = Lo_bound;
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wake_up_process(lo->lo_thread);
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return 0;
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out_putf:
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@ -907,12 +888,9 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
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spin_lock_irq(&lo->lo_lock);
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lo->lo_state = Lo_rundown;
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lo->lo_pending--;
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if (!lo->lo_pending)
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complete(&lo->lo_bh_done);
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spin_unlock_irq(&lo->lo_lock);
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wait_for_completion(&lo->lo_done);
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kthread_stop(lo->lo_thread);
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lo->lo_backing_file = NULL;
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@ -925,6 +903,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
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lo->lo_sizelimit = 0;
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lo->lo_encrypt_key_size = 0;
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lo->lo_flags = 0;
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lo->lo_thread = NULL;
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memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
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memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
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memset(lo->lo_file_name, 0, LO_NAME_SIZE);
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@ -1287,9 +1266,9 @@ static int __init loop_init(void)
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if (!lo->lo_queue)
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goto out_mem4;
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mutex_init(&lo->lo_ctl_mutex);
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init_completion(&lo->lo_done);
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init_completion(&lo->lo_bh_done);
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lo->lo_number = i;
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lo->lo_thread = NULL;
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init_waitqueue_head(&lo->lo_event);
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spin_lock_init(&lo->lo_lock);
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disk->major = LOOP_MAJOR;
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disk->first_minor = i;
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@ -59,10 +59,9 @@ struct loop_device {
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struct bio *lo_bio;
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struct bio *lo_biotail;
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int lo_state;
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struct completion lo_done;
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struct completion lo_bh_done;
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struct mutex lo_ctl_mutex;
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int lo_pending;
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struct task_struct *lo_thread;
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wait_queue_head_t lo_event;
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request_queue_t *lo_queue;
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};
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