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authorJun'ichi Nomura <j-nomura@ce.jp.nec.com>2009-04-02 19:55:27 +0100
committerAlasdair G Kergon <agk@redhat.com>2009-04-02 19:55:27 +0100
commitaea9058801c0acfa2831af1714da412dfb0018c2 (patch)
tree3a51498e150b84ef60580f1d2f5620785853a41a /drivers/md/dm-path-selector.c
parent5642b8a61a15436231adf27b2b1bd96901b623dd (diff)
downloadlinaro-lsk-aea9058801c0acfa2831af1714da412dfb0018c2.tar.gz
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/dm-path-selector.c')
-rw-r--r--drivers/md/dm-path-selector.c21
1 files changed, 3 insertions, 18 deletions
diff --git a/drivers/md/dm-path-selector.c b/drivers/md/dm-path-selector.c
index 96ea226155b..42c04f04a0c 100644
--- a/drivers/md/dm-path-selector.c
+++ b/drivers/md/dm-path-selector.c
@@ -17,9 +17,7 @@
struct ps_internal {
struct path_selector_type pst;
-
struct list_head list;
- long use;
};
#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)
down_read(&_ps_lock);
psi = __find_path_selector_type(name);
- if (psi) {
- if ((psi->use == 0) && !try_module_get(psi->pst.module))
- psi = NULL;
- else
- psi->use++;
- }
+ if (psi && !try_module_get(psi->pst.module))
+ psi = NULL;
up_read(&_ps_lock);
return psi;
@@ -84,11 +78,7 @@ void dm_put_path_selector(struct path_selector_type *pst)
if (!psi)
goto out;
- if (--psi->use == 0)
- module_put(psi->pst.module);
-
- BUG_ON(psi->use < 0);
-
+ module_put(psi->pst.module);
out:
up_read(&_ps_lock);
}
@@ -136,11 +126,6 @@ int dm_unregister_path_selector(struct path_selector_type *pst)
return -EINVAL;
}
- if (psi->use) {
- up_write(&_ps_lock);
- return -ETXTBSY;
- }
-
list_del(&psi->list);
up_write(&_ps_lock);