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Subject[PATCH 16/80] staging: lustre: obdclass: bug fixes for lu_device_type handling
Date
From: Fan Yong <fan.yong@intel.com>

There was no protection when inc/dec lu_device_type::ldt_device_nr,
which may caused the ldt_device_nr to be wrong and trigger assert.
This patch redefine lu_device_type::ldt_device_nr as atomic type.

There was no protection when add/del lu_device_type::ldt_linkage
into/from the global lu_device_types list, which may caused bad
address accessing. This patch uses the existing obd_types_lock
to protect related operations.

We do NOT need lu_types_stop() any longer. Such function scans
the global lu_device_types list, and for each type item on it
which has zerod lu_device_type::ldt_device_nr, call its stop()
method. In fact, the lu_device_type::ldt_device_nr only will be
zero when the last lu_device_fini() is called, and at that time,
inside the lu_device_fini(), its stop() method will be called.
So it is unnecessary to call the stop() again via lu_types_stop().

Signed-off-by: Fan Yong <fan.yong@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4604
Reviewed-on: http://review.whamcloud.com/8694
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
---
drivers/staging/lustre/lustre/include/lu_object.h | 3 +-
drivers/staging/lustre/lustre/llite/vvp_dev.c | 6 ---
drivers/staging/lustre/lustre/obdclass/lu_object.c | 34 ++++++++++----------
drivers/staging/lustre/lustre/obdclass/obd_mount.c | 1 -
4 files changed, 18 insertions(+), 26 deletions(-)

diff --git a/drivers/staging/lustre/lustre/include/lu_object.h b/drivers/staging/lustre/lustre/include/lu_object.h
index 6e25c1b..25c12d8 100644
--- a/drivers/staging/lustre/lustre/include/lu_object.h
+++ b/drivers/staging/lustre/lustre/include/lu_object.h
@@ -327,7 +327,7 @@ struct lu_device_type {
/**
* Number of existing device type instances.
*/
- unsigned ldt_device_nr;
+ atomic_t ldt_device_nr;
/**
* Linkage into a global list of all device types.
*
@@ -673,7 +673,6 @@ void lu_object_add(struct lu_object *before, struct lu_object *o);

int lu_device_type_init(struct lu_device_type *ldt);
void lu_device_type_fini(struct lu_device_type *ldt);
-void lu_types_stop(void);

/** @} ctors */

diff --git a/drivers/staging/lustre/lustre/llite/vvp_dev.c b/drivers/staging/lustre/lustre/llite/vvp_dev.c
index e623216..771c0bd 100644
--- a/drivers/staging/lustre/lustre/llite/vvp_dev.c
+++ b/drivers/staging/lustre/lustre/llite/vvp_dev.c
@@ -368,12 +368,6 @@ int cl_sb_fini(struct super_block *sb)
CERROR("Cannot cleanup cl-stack due to memory shortage.\n");
result = PTR_ERR(env);
}
- /*
- * If mount failed (sbi->ll_cl == NULL), and this there are no other
- * mounts, stop device types manually (this usually happens
- * automatically when last device is destroyed).
- */
- lu_types_stop();
return result;
}

diff --git a/drivers/staging/lustre/lustre/obdclass/lu_object.c b/drivers/staging/lustre/lustre/obdclass/lu_object.c
index 9b03059..0c00bf8 100644
--- a/drivers/staging/lustre/lustre/obdclass/lu_object.c
+++ b/drivers/staging/lustre/lustre/obdclass/lu_object.c
@@ -726,34 +726,31 @@ int lu_device_type_init(struct lu_device_type *ldt)
{
int result = 0;

+ atomic_set(&ldt->ldt_device_nr, 0);
INIT_LIST_HEAD(&ldt->ldt_linkage);
if (ldt->ldt_ops->ldto_init)
result = ldt->ldt_ops->ldto_init(ldt);
- if (result == 0)
+
+ if (!result) {
+ spin_lock(&obd_types_lock);
list_add(&ldt->ldt_linkage, &lu_device_types);
+ spin_unlock(&obd_types_lock);
+ }
+
return result;
}
EXPORT_SYMBOL(lu_device_type_init);

void lu_device_type_fini(struct lu_device_type *ldt)
{
+ spin_lock(&obd_types_lock);
list_del_init(&ldt->ldt_linkage);
+ spin_unlock(&obd_types_lock);
if (ldt->ldt_ops->ldto_fini)
ldt->ldt_ops->ldto_fini(ldt);
}
EXPORT_SYMBOL(lu_device_type_fini);

-void lu_types_stop(void)
-{
- struct lu_device_type *ldt;
-
- list_for_each_entry(ldt, &lu_device_types, ldt_linkage) {
- if (ldt->ldt_device_nr == 0 && ldt->ldt_ops->ldto_stop)
- ldt->ldt_ops->ldto_stop(ldt);
- }
-}
-EXPORT_SYMBOL(lu_types_stop);
-
/**
* Global list of all sites on this node
*/
@@ -1082,8 +1079,10 @@ EXPORT_SYMBOL(lu_device_put);
*/
int lu_device_init(struct lu_device *d, struct lu_device_type *t)
{
- if (t->ldt_device_nr++ == 0 && t->ldt_ops->ldto_start)
+ if (atomic_inc_return(&t->ldt_device_nr) == 1 &&
+ t->ldt_ops->ldto_start)
t->ldt_ops->ldto_start(t);
+
memset(d, 0, sizeof(*d));
atomic_set(&d->ld_ref, 0);
d->ld_type = t;
@@ -1098,9 +1097,8 @@ EXPORT_SYMBOL(lu_device_init);
*/
void lu_device_fini(struct lu_device *d)
{
- struct lu_device_type *t;
+ struct lu_device_type *t = d->ld_type;

- t = d->ld_type;
if (d->ld_obd) {
d->ld_obd->obd_lu_dev = NULL;
d->ld_obd = NULL;
@@ -1109,8 +1107,10 @@ void lu_device_fini(struct lu_device *d)
lu_ref_fini(&d->ld_reference);
LASSERTF(atomic_read(&d->ld_ref) == 0,
"Refcount is %u\n", atomic_read(&d->ld_ref));
- LASSERT(t->ldt_device_nr > 0);
- if (--t->ldt_device_nr == 0 && t->ldt_ops->ldto_stop)
+ LASSERT(atomic_read(&t->ldt_device_nr) > 0);
+
+ if (atomic_dec_and_test(&t->ldt_device_nr) &&
+ t->ldt_ops->ldto_stop)
t->ldt_ops->ldto_stop(t);
}
EXPORT_SYMBOL(lu_device_fini);
diff --git a/drivers/staging/lustre/lustre/obdclass/obd_mount.c b/drivers/staging/lustre/lustre/obdclass/obd_mount.c
index 4931e37..33d6c42 100644
--- a/drivers/staging/lustre/lustre/obdclass/obd_mount.c
+++ b/drivers/staging/lustre/lustre/obdclass/obd_mount.c
@@ -670,7 +670,6 @@ int lustre_common_put_super(struct super_block *sb)
}
/* Drop a ref to the mounted disk */
lustre_put_lsi(sb);
- lu_types_stop();
return rc;
}
EXPORT_SYMBOL(lustre_common_put_super);
--
1.7.1
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