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authorPetr Uzel <petr.uzel@suse.cz>2011-03-03 11:48:50 -0500
committerJens Axboe <jaxboe@fusionio.com>2011-03-03 11:53:25 -0500
commitfd51469fb68b987032e46297e0a4fe9020063c20 (patch)
treea108634afe0a0b2113f5df6ef5c00be2087f51c3 /drivers/block/loop.c
parent2d3a8497f8cc5aca14b722cd37d51f6c15ff9f74 (diff)
block: kill loop_mutex
Following steps lead to deadlock in kernel: dd if=/dev/zero of=img bs=512 count=1000 losetup -f img mkfs.ext2 /dev/loop0 mount -t ext2 -o loop /dev/loop0 mnt umount mnt/ Stacktrace: [<c102ec04>] irq_exit+0x36/0x59 [<c101502c>] smp_apic_timer_interrupt+0x6b/0x75 [<c127f639>] apic_timer_interrupt+0x31/0x38 [<c101df88>] mutex_spin_on_owner+0x54/0x5b [<fe2250e9>] lo_release+0x12/0x67 [loop] [<c10c4eae>] __blkdev_put+0x7c/0x10c [<c10a4da5>] fput+0xd5/0x1aa [<fe2250cf>] loop_clr_fd+0x1a9/0x1b1 [loop] [<fe225110>] lo_release+0x39/0x67 [loop] [<c10c4eae>] __blkdev_put+0x7c/0x10c [<c10a59d9>] deactivate_locked_super+0x17/0x36 [<c10b6f37>] sys_umount+0x27e/0x2a5 [<c10b6f69>] sys_oldumount+0xb/0xe [<c1002897>] sysenter_do_call+0x12/0x26 [<ffffffff>] 0xffffffff Regression since 2a48fc0ab24241755dc9, which introduced the private loop_mutex as part of the BKL removal process. As per [1], the mutex can be safely removed. [1] http://www.gossamer-threads.com/lists/linux/kernel/1341930 Addresses: https://bugzilla.novell.com/show_bug.cgi?id=669394 Addresses: https://bugzilla.kernel.org/show_bug.cgi?id=29172 Signed-off-by: Petr Uzel <petr.uzel@suse.cz> Cc: stable@kernel.org Reviewed-by: Nikanth Karthikesan <knikanth@suse.de> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'drivers/block/loop.c')
-rw-r--r--drivers/block/loop.c5
1 files changed, 0 insertions, 5 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 49e6a545eb63..dbf31ec9114d 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -78,7 +78,6 @@
#include <asm/uaccess.h>
-static DEFINE_MUTEX(loop_mutex);
static LIST_HEAD(loop_devices);
static DEFINE_MUTEX(loop_devices_mutex);
@@ -1501,11 +1500,9 @@ static int lo_open(struct block_device *bdev, fmode_t mode)
{
struct loop_device *lo = bdev->bd_disk->private_data;
- mutex_lock(&loop_mutex);
mutex_lock(&lo->lo_ctl_mutex);
lo->lo_refcnt++;
mutex_unlock(&lo->lo_ctl_mutex);
- mutex_unlock(&loop_mutex);
return 0;
}
@@ -1515,7 +1512,6 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
struct loop_device *lo = disk->private_data;
int err;
- mutex_lock(&loop_mutex);
mutex_lock(&lo->lo_ctl_mutex);
if (--lo->lo_refcnt)
@@ -1540,7 +1536,6 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
out:
mutex_unlock(&lo->lo_ctl_mutex);
out_unlocked:
- mutex_unlock(&loop_mutex);
return 0;
}