diff options
author | Jun'ichi Nomura <j-nomura@ce.jp.nec.com> | 2009-04-02 14:55:27 -0400 |
---|---|---|
committer | Alasdair G Kergon <agk@redhat.com> | 2009-04-02 14:55:27 -0400 |
commit | aea9058801c0acfa2831af1714da412dfb0018c2 (patch) | |
tree | 3a51498e150b84ef60580f1d2f5620785853a41a /drivers/md | |
parent | 5642b8a61a15436231adf27b2b1bd96901b623dd (diff) |
dm: path selector use module refcount directly
Fix refcount corruption in dm-path-selector
Refcounting with non-atomic ops under shared lock will corrupt the counter
in multi-processor system and may trigger BUG_ON().
Use module refcount.
# same approach as dm-target-use-module-refcount-directly.patch here
# https://www.redhat.com/archives/dm-devel/2008-December/msg00075.html
Typical oops:
kernel BUG at linux-2.6.29-rc3/drivers/md/dm-path-selector.c:90!
Pid: 11148, comm: dmsetup Not tainted 2.6.29-rc3-nm #1
dm_put_path_selector+0x4d/0x61 [dm_multipath]
Call Trace:
[<ffffffffa031d3f9>] free_priority_group+0x33/0xb3 [dm_multipath]
[<ffffffffa031d4aa>] free_multipath+0x31/0x67 [dm_multipath]
[<ffffffffa031d50d>] multipath_dtr+0x2d/0x32 [dm_multipath]
[<ffffffffa015d6c2>] dm_table_destroy+0x64/0xd8 [dm_mod]
[<ffffffffa015b73a>] __unbind+0x46/0x4b [dm_mod]
[<ffffffffa015b79f>] dm_swap_table+0x60/0x14d [dm_mod]
[<ffffffffa015f963>] dev_suspend+0xfd/0x177 [dm_mod]
[<ffffffffa0160250>] dm_ctl_ioctl+0x24c/0x29c [dm_mod]
[<ffffffff80288cd3>] ? get_page_from_freelist+0x49c/0x61d
[<ffffffffa015f866>] ? dev_suspend+0x0/0x177 [dm_mod]
[<ffffffff802bf05c>] vfs_ioctl+0x2a/0x77
[<ffffffff802bf4f1>] do_vfs_ioctl+0x448/0x4a0
[<ffffffff802bf5a0>] sys_ioctl+0x57/0x7a
[<ffffffff8020c05b>] system_call_fastpath+0x16/0x1b
Cc: stable@kernel.org
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r-- | drivers/md/dm-path-selector.c | 21 |
1 files changed, 3 insertions, 18 deletions
diff --git a/drivers/md/dm-path-selector.c b/drivers/md/dm-path-selector.c index 96ea226155b1..42c04f04a0c4 100644 --- a/drivers/md/dm-path-selector.c +++ b/drivers/md/dm-path-selector.c | |||
@@ -17,9 +17,7 @@ | |||
17 | 17 | ||
18 | struct ps_internal { | 18 | struct ps_internal { |
19 | struct path_selector_type pst; | 19 | struct path_selector_type pst; |
20 | |||
21 | struct list_head list; | 20 | struct list_head list; |
22 | long use; | ||
23 | }; | 21 | }; |
24 | 22 | ||
25 | #define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst) | 23 | #define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst) |
@@ -45,12 +43,8 @@ static struct ps_internal *get_path_selector(const char *name) | |||
45 | 43 | ||
46 | down_read(&_ps_lock); | 44 | down_read(&_ps_lock); |
47 | psi = __find_path_selector_type(name); | 45 | psi = __find_path_selector_type(name); |
48 | if (psi) { | 46 | if (psi && !try_module_get(psi->pst.module)) |
49 | if ((psi->use == 0) && !try_module_get(psi->pst.module)) | 47 | psi = NULL; |
50 | psi = NULL; | ||
51 | else | ||
52 | psi->use++; | ||
53 | } | ||
54 | up_read(&_ps_lock); | 48 | up_read(&_ps_lock); |
55 | 49 | ||
56 | return psi; | 50 | return psi; |
@@ -84,11 +78,7 @@ void dm_put_path_selector(struct path_selector_type *pst) | |||
84 | if (!psi) | 78 | if (!psi) |
85 | goto out; | 79 | goto out; |
86 | 80 | ||
87 | if (--psi->use == 0) | 81 | module_put(psi->pst.module); |
88 | module_put(psi->pst.module); | ||
89 | |||
90 | BUG_ON(psi->use < 0); | ||
91 | |||
92 | out: | 82 | out: |
93 | up_read(&_ps_lock); | 83 | up_read(&_ps_lock); |
94 | } | 84 | } |
@@ -136,11 +126,6 @@ int dm_unregister_path_selector(struct path_selector_type *pst) | |||
136 | return -EINVAL; | 126 | return -EINVAL; |
137 | } | 127 | } |
138 | 128 | ||
139 | if (psi->use) { | ||
140 | up_write(&_ps_lock); | ||
141 | return -ETXTBSY; | ||
142 | } | ||
143 | |||
144 | list_del(&psi->list); | 129 | list_del(&psi->list); |
145 | 130 | ||
146 | up_write(&_ps_lock); | 131 | up_write(&_ps_lock); |