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 <torvalds@osdl.org>
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 9dc294a..3c74ea7 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -74,7 +74,6 @@
#include <linux/completion.h>
#include <linux/highmem.h>
#include <linux/gfp.h>
-#include <linux/kthread.h>
#include <asm/uaccess.h>
@@ -579,6 +578,8 @@
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 @@
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 @@
break;
}
+ complete(&lo->lo_done);
return 0;
}
@@ -739,7 +746,6 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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);