[PATCH 04/12] target: Move subdev release logic into ->release() callback

Nicholas A. Bellinger
2011-02-04T06:45:20Z

This patch moves the se_free_virtual_device() / se_subsystem_api->free_device()
and subsequent release of struct se_subsystem_dev memory to inside of the
configfs callback target_core_dev_item_ops->release() called from within
fs/configfs/item.c:config_item_cleanup() context. This patch resolves the
following SLUB 'Poison overwritten' warning when calling target_core_drop_subdev()
-> kfree(se_dev) directly after config_item_put():

[ 5147.638639] =============================================================================
[ 5147.638959] BUG kmalloc-4096: Poison overwritten
[ 5147.639124] -----------------------------------------------------------------------------
[ 5147.639124]
[ 5147.639294] INFO: 0xffff88000d2f887c-0xffff88000d2f887c. First byte 0x6a instead of 0x6b
[ 5147.639294] INFO: Allocated in kzalloc+0xf/0x11 [target_core_mod] age=2602 cpu=0 pid=14639
[ 5147.639294] INFO: Freed in target_core_drop_subdev+0x18d/0x199 [target_core_mod] age=25 cpu=0 pid=14654
[ 5147.639294] INFO: Slab 0xffffea00002e2640 objects=7 used=1 fp=0xffff88000d2f8000 flags=0x1000000000040c1
[ 5147.639294] INFO: Object 0xffff88000d2f8000 @offset=0 fp=0xffff88000d2fb0d8

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 | 64 ++++++++++++++++-----------------
1 files changed, 31 insertions(+), 33 deletions(-)

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 9e74aa1..a9e0c66 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -2003,9 +2003,35 @@ static void target_core_dev_release(struct config_item *item)
{
struct se_subsystem_dev *se_dev = container_of(to_config_group(item),
struct se_subsystem_dev, se_dev_group);
+ struct se_hba *hba = item_to_hba(&se_dev->se_dev_hba->hba_group.cg_item);
+ struct se_subsystem_api *t = hba->transport;
struct config_group *dev_cg = &se_dev->se_dev_group;

kfree(dev_cg->default_groups);
+ /*
+ * This pointer will set when the storage is enabled with:
+ *`echo 1 > $CONFIGFS/core/$HBA/$DEV/dev_enable`
+ */
+ if (se_dev->se_dev_ptr) {
+ printk(KERN_INFO "Target_Core_ConfigFS: Calling se_free_"
+ "virtual_device() for se_dev_ptr: %p\n",
+ se_dev->se_dev_ptr);
+
+ se_free_virtual_device(se_dev->se_dev_ptr, hba);
+ } else {
+ /*
+ * Release struct se_subsystem_dev->se_dev_su_ptr..
+ */
+ printk(KERN_INFO "Target_Core_ConfigFS: Calling t->free_"
+ "device() for se_dev_su_ptr: %p\n",
+ se_dev->se_dev_su_ptr);
+
+ t->free_device(se_dev->se_dev_su_ptr);
+ }
+
+ printk(KERN_INFO "Target_Core_ConfigFS: Deallocating se_subsystem"
+ "_dev_t: %p\n", se_dev);
+ kfree(se_dev);
}

static ssize_t target_core_dev_show(struct config_item *item,
@@ -2799,13 +2825,11 @@ static void target_core_drop_subdev(
struct se_subsystem_api *t;
struct config_item *df_item;
struct config_group *dev_cg, *tg_pt_gp_cg;
- int i, ret;
+ int i;

hba = item_to_hba(&se_dev->se_dev_hba->hba_group.cg_item);

- if (mutex_lock_interruptible(&hba->hba_access_mutex))
- goto out;
-
+ mutex_lock(&hba->hba_access_mutex);
t = hba->transport;

spin_lock(&se_global->g_device_lock);
@@ -2828,38 +2852,12 @@ static void target_core_drop_subdev(
dev_cg->default_groups[i] = NULL;
config_item_put(df_item);
}
-
- config_item_put(item);
/*
- * This pointer will set when the storage is enabled with:
- * `echo 1 > $CONFIGFS/core/$HBA/$DEV/dev_enable`
+ * The releasing of se_dev and associated se_dev->se_dev_ptr is done
+ * from target_core_dev_item_ops->release() ->target_core_dev_release().
*/
- if (se_dev->se_dev_ptr) {
- printk(KERN_INFO "Target_Core_ConfigFS: Calling se_free_"
- "virtual_device() for se_dev_ptr: %p\n",
- se_dev->se_dev_ptr);
-
- ret = se_free_virtual_device(se_dev->se_dev_ptr, hba);
- if (ret < 0)
- goto hba_out;
- } else {
- /*
- * Release struct se_subsystem_dev->se_dev_su_ptr..
- */
- printk(KERN_INFO "Target_Core_ConfigFS: Calling t->free_"
- "device() for se_dev_su_ptr: %p\n",
- se_dev->se_dev_su_ptr);
-
- t->free_device(se_dev->se_dev_su_ptr);
- }
-
- printk(KERN_INFO "Target_Core_ConfigFS: Deallocating se_subsystem"
- "_dev_t: %p\n", se_dev);
-
-hba_out:
+ config_item_put(item);
mutex_unlock(&hba->hba_access_mutex);
-out:
- kfree(se_dev);
}

static struct configfs_group_operations target_core_hba_group_ops = {
--
1.7.4