From 09c0dc68625c06f5b1e786aad0d5369b592179e6 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Mon, 26 Jun 2006 11:55:42 -0700 Subject: [PATCH] Revert "[PATCH] kthread: update loop.c to use kthread" This reverts commit c7b2eff059fcc2d1b7085ee3d84b79fd657a537b. Hugh Dickins explains: "It seems too little tested: "losetup -d /dev/loop0" fails with EINVAL because nothing sets lo_thread; but even when you patch loop_thread() to set lo->lo_thread = current, it can't survive more than a few dozen iterations of the loop below (with a tmpfs mounted on /tst): j=0 cp /dev/zero /tst while : do let j=j+1 echo "Doing pass $j" losetup /dev/loop0 /tst/zero mkfs -t ext2 -b 1024 /dev/loop0 >/dev/null 2>&1 mount -t ext2 /dev/loop0 /mnt umount /mnt losetup -d /dev/loop0 done it collapses with failed ioctl then BUG_ON(!bio). I think the original lo_done completion was more subtle and safe than the kthread conversion has allowed for." Signed-off-by: Linus Torvalds --- drivers/block/loop.c | 24 +++++++++++++----------- include/linux/loop.h | 2 +- 2 files changed, 14 insertions(+), 12 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 9dc294a74953..3c74ea729fc7 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -74,7 +74,6 @@ #include #include #include -#include #include @@ -579,6 +578,8 @@ 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 @@ -591,6 +592,11 @@ static int loop_thread(void *data) lo->lo_state = Lo_bound; lo->lo_pending = 1; + /* + * complete it, we are running + */ + complete(&lo->lo_done); + for (;;) { int pending; @@ -623,6 +629,7 @@ static int loop_thread(void *data) break; } + complete(&lo->lo_done); return 0; } @@ -739,7 +746,6 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file, unsigned lo_blocksize; int lo_flags = 0; int error; - struct task_struct *tsk; loff_t size; /* This is safe, since we have a reference from open(). */ @@ -833,11 +839,10 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file, set_blocksize(bdev, lo_blocksize); - tsk = kthread_run(loop_thread, lo, "loop%d", lo->lo_number); - if (IS_ERR(tsk)) { - error = PTR_ERR(tsk); + error = kernel_thread(loop_thread, lo, CLONE_KERNEL); + if (error < 0) goto out_putf; - } + wait_for_completion(&lo->lo_done); return 0; out_putf: @@ -893,9 +898,6 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) if (lo->lo_state != Lo_bound) return -ENXIO; - if (!lo->lo_thread) - return -EINVAL; - if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */ return -EBUSY; @@ -909,7 +911,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) complete(&lo->lo_bh_done); spin_unlock_irq(&lo->lo_lock); - kthread_stop(lo->lo_thread); + wait_for_completion(&lo->lo_done); lo->lo_backing_file = NULL; @@ -922,7 +924,6 @@ 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); @@ -1287,6 +1288,7 @@ 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; spin_lock_init(&lo->lo_lock); diff --git a/include/linux/loop.h b/include/linux/loop.h index bf3d2345ce99..e76c7611d6cc 100644 --- a/include/linux/loop.h +++ b/include/linux/loop.h @@ -59,7 +59,7 @@ struct loop_device { struct bio *lo_bio; struct bio *lo_biotail; int lo_state; - struct task_struct *lo_thread; + struct completion lo_done; struct completion lo_bh_done; struct mutex lo_ctl_mutex; int lo_pending; -- 2.20.1