projects / ipfire-2.x.git / blame
| Commit | Line | Data |
|---|---|---|
| 2cb7cef9 BS |
1 | From: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> |
| 2 | Subject: dm: Fix lock dependency warning for request based dm | |
| 3 | References: bnc#477927 | |
| 4 | ||
| 5 | > > From: Christof Schmitt <christof.schmitt@de.ibm.com> | |
| 6 | > > | |
| 7 | > > Testing with request based dm multipathing and lock dependency checking | |
| 8 | > > revealed this problem. Fix this by disabling interrupts when acquiring the | |
| 9 | > > map_lock from the ioctl call in __bind and __unbind. | |
| 10 | > > | |
| 11 | > > It seems that the problem has been introduced with this patch: | |
| 12 | > > http://lkml.indiana.edu/hypermail/linux/kernel/0810.0/1067.html | |
| 13 | ||
| 14 | Thank you for your testing request-based dm-multipath and the patch. | |
| 15 | ||
| 16 | Attached is a patch to fix it. | |
| 17 | Since request-based dm gets map_lock after taking queue_lock with | |
| 18 | interrupt disabled, we have to use save/restore variant. | |
| 19 | (By the way, although lockdep warns the deadlock possibility, currently | |
| 20 | there should be no such code path in request-based dm where request_fn | |
| 21 | is called from the interrupt context.) | |
| 22 | ||
| 23 | I have done simple build and boot testings, but haven't done other | |
| 24 | testings (e.g. stress testing) yet. | |
| 25 | I will include this patch to the next update after such testings. | |
| 26 | ||
| 27 | Thanks, | |
| 28 | Kiyoshi Ueda | |
| 29 | ||
| 30 | Signed-off-by: Nikanth karthikesan <knikanth@suse.de> | |
| 31 | ||
| 32 | Index: linux-2.6.27-SLE11_BRANCH/drivers/md/dm.c | |
| 33 | =================================================================== | |
| 34 | --- linux-2.6.27-SLE11_BRANCH.orig/drivers/md/dm.c | |
| 35 | +++ linux-2.6.27-SLE11_BRANCH/drivers/md/dm.c | |
| 36 | @@ -525,12 +525,13 @@ static int queue_io(struct mapped_device | |
| 37 | struct dm_table *dm_get_table(struct mapped_device *md) | |
| 38 | { | |
| 39 | struct dm_table *t; | |
| 40 | + unsigned long flags; | |
| 41 | ||
| 42 | - read_lock(&md->map_lock); | |
| 43 | + read_lock_irqsave(&md->map_lock, flags); | |
| 44 | t = md->map; | |
| 45 | if (t) | |
| 46 | dm_table_get(t); | |
| 47 | - read_unlock(&md->map_lock); | |
| 48 | + read_unlock_irqrestore(&md->map_lock, flags); | |
| 49 | ||
| 50 | return t; | |
| 51 | } | |
| 52 | @@ -1913,6 +1914,7 @@ static int __bind(struct mapped_device * | |
| 53 | { | |
| 54 | struct request_queue *q = md->queue; | |
| 55 | sector_t size; | |
| 56 | + unsigned long flags; | |
| 57 | ||
| 58 | size = dm_table_get_size(t); | |
| 59 | ||
| 60 | @@ -1942,7 +1944,7 @@ static int __bind(struct mapped_device * | |
| 61 | if (dm_table_request_based(t) && !blk_queue_stopped(q)) | |
| 62 | stop_queue(q); | |
| 63 | ||
| 64 | - write_lock(&md->map_lock); | |
| 65 | + write_lock_irqsave(&md->map_lock, flags); | |
| 66 | md->map = t; | |
| 67 | dm_table_set_restrictions(t, q); | |
| 68 | dm_table_set_integrity(t, md); | |
| 69 | @@ -1951,7 +1953,7 @@ static int __bind(struct mapped_device * | |
| 70 | } else { | |
| 71 | set_disk_ro(md->disk, 0); | |
| 72 | } | |
| 73 | - write_unlock(&md->map_lock); | |
| 74 | + write_unlock_irqrestore(&md->map_lock, flags); | |
| 75 | ||
| 76 | return 0; | |
| 77 | } | |
| 78 | @@ -1959,14 +1961,15 @@ static int __bind(struct mapped_device * | |
| 79 | static void __unbind(struct mapped_device *md) | |
| 80 | { | |
| 81 | struct dm_table *map = md->map; | |
| 82 | + unsigned long flags; | |
| 83 | ||
| 84 | if (!map) | |
| 85 | return; | |
| 86 | ||
| 87 | dm_table_event_callback(map, NULL, NULL); | |
| 88 | - write_lock(&md->map_lock); | |
| 89 | + write_lock_irqsave(&md->map_lock, flags); | |
| 90 | md->map = NULL; | |
| 91 | - write_unlock(&md->map_lock); | |
| 92 | + write_unlock_irqrestore(&md->map_lock, flags); | |
| 93 | dm_table_destroy(map); | |
| 94 | } | |
| 95 |