[PATCH 06/12] target: Move core_alua_free_tg_pt_gp() into ->release() callback

Nicholas A. Bellinger
2011-02-04T06:45:24Z

This patch moves the core_alua_free_tg_pt_gp() and subsequent release of
struct t10_alua_tg_pt_gp memory to inside of the configfs callback
target_core_alua_tg_pt_gp_ops->release() called from within
fs/configfs/item.c:config_item_cleanup() context. This patch resolves
the following SLUB 'Poison overwritten' warning when calling
core_alua_free_tg_pt_gp() -> kfree(tg_pt_gp) directly after config_item_put():

[10703.173250] =============================================================================
[10703.173250] BUG t10_alua_tg_pt_gp_cache: Poison overwritten
[10703.173250] -----------------------------------------------------------------------------
[10703.173250]
[10703.173250] INFO: 0xffff88001eb1637c-0xffff88001eb1637c. First byte 0x6a instead of 0x6b
[10703.173250] INFO: Allocated in core_alua_allocate_tg_pt_gp+0x21/0x126 [target_core_mod] age=2297 cpu=0 pid=21770
[10703.173250] INFO: Freed in core_alua_free_tg_pt_gp+0xf2/0xfe [target_core_mod] age=67 cpu=0 pid=21775
[10703.173250] INFO: Slab 0xffffea00006b6cd0 objects=21 used=0 fp=0xffff88001eb16000 flags=0x100000000004080
[10703.173250] INFO: Object 0xffff88001eb16300 @offset=768 fp=0xffff88001eb16480

Cc: Joel Becker <jlbec@evilplan.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
---
drivers/target/target_core_configfs.c | 20 +++++++++++++++++---
1 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index a745101..53742bc 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -2614,7 +2614,16 @@ static struct configfs_attribute *target_core_alua_tg_pt_gp_attrs[] = {
NULL,
};

+static void target_core_alua_tg_pt_gp_release(struct config_item *item)
+{
+ struct t10_alua_tg_pt_gp *tg_pt_gp = container_of(to_config_group(item),
+ struct t10_alua_tg_pt_gp, tg_pt_gp_group);
+
+ core_alua_free_tg_pt_gp(tg_pt_gp);
+}
+
static struct configfs_item_operations target_core_alua_tg_pt_gp_ops = {
+ .release = target_core_alua_tg_pt_gp_release,
.show_attribute = target_core_alua_tg_pt_gp_attr_show,
.store_attribute = target_core_alua_tg_pt_gp_attr_store,
};
@@ -2667,9 +2676,11 @@ static void target_core_alua_drop_tg_pt_gp(
printk(KERN_INFO "Target_Core_ConfigFS: Releasing ALUA Target Port"
" Group: alua/tg_pt_gps/%s, ID: %hu\n",
config_item_name(item), tg_pt_gp->tg_pt_gp_id);
-
+ /*
+ * core_alua_free_tg_pt_gp() is called from target_core_alua_tg_pt_gp_ops->release()
+ * -> target_core_alua_tg_pt_gp_release().
+ */
config_item_put(item);
- core_alua_free_tg_pt_gp(tg_pt_gp);
}

static struct configfs_group_operations target_core_alua_tg_pt_gps_group_ops = {
@@ -2854,7 +2865,10 @@ static void target_core_drop_subdev(
config_item_put(df_item);
}
kfree(tg_pt_gp_cg->default_groups);
- core_alua_free_tg_pt_gp(T10_ALUA(se_dev)->default_tg_pt_gp);
+ /*
+ * core_alua_free_tg_pt_gp() is called from ->default_tg_pt_gp
+ * directly from target_core_alua_tg_pt_gp_release().
+ */
T10_ALUA(se_dev)->default_tg_pt_gp = NULL;

dev_cg = &se_dev->se_dev_group;
--
1.7.4