Hi
You are right, thanks for the review. I grepped for other uses of
dm_table_put and they seem correct - just these two were bad.
Alasdair: push this patch to Linus soon.
Another point: it looks somehow scary to free the table before unlocking
_hash_lock --- most of the time, _hash_lock is took only on behalf of
userspace ioctls (no problem with that), but it is also took in
dm_copy_name_and_uuid that can be called from uevent code:
dm_table_event -> event_callback -> dm_send_uevents -> takes _hash_lock
And dm_table_event is called directly from targets, targets wait for
dm_table_event to finish in their destructor --- so calling the destructor
with locked _hash_lock seems to be a deadlock possibility --- what do you
think?
Mikulas
On Tue, 6 Jan 2009, Kiyoshi Ueda wrote:
> Hi Alasdair, Mikulas,
>
> Although I'm not sure this is correct, don't we need to convert
> the following 2 dm_table_put()s to dm_table_destroy()?
> Otherwise, the created table won't be destroyed and memory leak
> will happen in such error cases?
>
> drivers/md/dm-ioctl.c:table_load()
> 1060 r = dm_table_create(&t, get_mode(param), param->target_count, md);
> 1061 if (r)
> 1062 goto out;
> 1063
> 1064 r = populate_table(t, param, param_size);
> 1065 if (r) {
> 1066 dm_table_put(t);
> 1067 goto out;
> 1068 }
> 1069
> 1070 down_write(&_hash_lock);
> 1071 hc = dm_get_mdptr(md);
> 1072 if (!hc || hc->md != md) {
> 1073 DMWARN("device has been removed from the dev hash table.");
> 1074 dm_table_put(t);
> 1075 up_write(&_hash_lock);
> 1076 r = -ENXIO;
> 1077 goto out;
> 1078 }
>
> Thanks,
> Kiyoshi Ueda
>
Fix an error introduced in dm-table-rework-reference-counting.patch.
When there is failure after table initialization, we need to use
dm_table_destroy, not dm_table_put, to free the table.
dm_table_put may be used only after dm_table_get.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
CC: Kiyoshi Ueda <k-ueda@xxxxxxxxxxxxx>
---
drivers/md/dm-ioctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6.28-devel/drivers/md/dm-ioctl.c
===================================================================
--- linux-2.6.28-devel.orig/drivers/md/dm-ioctl.c 2009-01-06 22:06:01.000000000 +0100
+++ linux-2.6.28-devel/drivers/md/dm-ioctl.c 2009-01-06 22:07:05.000000000 +0100
@@ -1063,7 +1063,7 @@ static int table_load(struct dm_ioctl *p
r = populate_table(t, param, param_size);
if (r) {
- dm_table_put(t);
+ dm_table_destroy(t);
goto out;
}
@@ -1071,7 +1071,7 @@ static int table_load(struct dm_ioctl *p
hc = dm_get_mdptr(md);
if (!hc || hc->md != md) {
DMWARN("device has been removed from the dev hash table.");
- dm_table_put(t);
+ dm_table_destroy(t);
up_write(&_hash_lock);
r = -ENXIO;
goto out;
--
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