| Message ID | 154949781345.10620.8278067573811049130.stgit@noble.brown (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | lustre: Assorted cleanups for obdclass | expand |
> Safe module loading requires that we try_module_get() in a context > where the module cannot be unloaded, typically prodected by > a spinlock that module-unload has to take. > This doesn't currently happen in class_get_type(). > > There is a per-type spinlock, but it is almost entirely unused, and > cannot be used to protect the module from being unloaded. > > So discard ->obd_type_lock, and ensure that __class_search_type() and > try_module_get() are both called while obd_types_lock is held - this > prevent class_unregister_type() from completing (so the 'type' won't get > freed. That is always called from a module-unload function - if it > has got that far, try_module_get() will fail. > > So also check the return status of try_module_get(). Reviewed-by: James Simmons <jsimmons@infradead.org> > Signed-off-by: NeilBrown <neilb@suse.com> > --- > drivers/staging/lustre/lustre/include/obd.h | 1 - > drivers/staging/lustre/lustre/obdclass/genops.c | 24 ++++++++++++++--------- > 2 files changed, 15 insertions(+), 10 deletions(-) > > diff --git a/drivers/staging/lustre/lustre/include/obd.h b/drivers/staging/lustre/lustre/include/obd.h > index 171d2c214be6..463ab680b524 100644 > --- a/drivers/staging/lustre/lustre/include/obd.h > +++ b/drivers/staging/lustre/lustre/include/obd.h > @@ -106,7 +106,6 @@ struct obd_type { > char *typ_name; > int typ_refcnt; > struct lu_device_type *typ_lu; > - spinlock_t obd_type_lock; > struct kobject *typ_kobj; > }; > > diff --git a/drivers/staging/lustre/lustre/obdclass/genops.c b/drivers/staging/lustre/lustre/obdclass/genops.c > index a174f538dd0d..dad21d9fa328 100644 > --- a/drivers/staging/lustre/lustre/obdclass/genops.c > +++ b/drivers/staging/lustre/lustre/obdclass/genops.c > @@ -109,35 +109,42 @@ static struct obd_type *class_search_type(const char *name) > > static struct obd_type *class_get_type(const char *name) > { > - struct obd_type *type = class_search_type(name); > + struct obd_type *type; > + > + spin_lock(&obd_types_lock); > + type = __class_search_type(name); > > if (!type) { > const char *modname = name; > > + spin_unlock(&obd_types_lock); > if (!request_module("%s", modname)) { > CDEBUG(D_INFO, "Loaded module '%s'\n", modname); > - type = class_search_type(name); > } else { > LCONSOLE_ERROR_MSG(0x158, "Can't load module '%s'\n", > modname); > } > + spin_lock(&obd_types_lock); > + type = __class_search_type(name); > } > if (type) { > - spin_lock(&type->obd_type_lock); > - type->typ_refcnt++; > - try_module_get(type->typ_dt_ops->owner); > - spin_unlock(&type->obd_type_lock); > + if (try_module_get(type->typ_dt_ops->owner)) > + type->typ_refcnt++; > + else > + type = NULL; > } > + spin_unlock(&obd_types_lock); > return type; > } > > void class_put_type(struct obd_type *type) > { > LASSERT(type); > - spin_lock(&type->obd_type_lock); > + spin_lock(&obd_types_lock); > + LASSERT(type->typ_refcnt > 0); > type->typ_refcnt--; > module_put(type->typ_dt_ops->owner); > - spin_unlock(&type->obd_type_lock); > + spin_unlock(&obd_types_lock); > } > > static void class_sysfs_release(struct kobject *kobj) > @@ -206,7 +213,6 @@ int class_register_type(struct obd_ops *dt_ops, struct md_ops *md_ops, > if (md_ops) > *type->typ_md_ops = *md_ops; > strcpy(type->typ_name, name); > - spin_lock_init(&type->obd_type_lock); > > type->typ_debugfs_entry = debugfs_create_dir(type->typ_name, > debugfs_lustre_root); > > >
diff --git a/drivers/staging/lustre/lustre/include/obd.h b/drivers/staging/lustre/lustre/include/obd.h index 171d2c214be6..463ab680b524 100644 --- a/drivers/staging/lustre/lustre/include/obd.h +++ b/drivers/staging/lustre/lustre/include/obd.h @@ -106,7 +106,6 @@ struct obd_type { char *typ_name; int typ_refcnt; struct lu_device_type *typ_lu; - spinlock_t obd_type_lock; struct kobject *typ_kobj; }; diff --git a/drivers/staging/lustre/lustre/obdclass/genops.c b/drivers/staging/lustre/lustre/obdclass/genops.c index a174f538dd0d..dad21d9fa328 100644 --- a/drivers/staging/lustre/lustre/obdclass/genops.c +++ b/drivers/staging/lustre/lustre/obdclass/genops.c @@ -109,35 +109,42 @@ static struct obd_type *class_search_type(const char *name) static struct obd_type *class_get_type(const char *name) { - struct obd_type *type = class_search_type(name); + struct obd_type *type; + + spin_lock(&obd_types_lock); + type = __class_search_type(name); if (!type) { const char *modname = name; + spin_unlock(&obd_types_lock); if (!request_module("%s", modname)) { CDEBUG(D_INFO, "Loaded module '%s'\n", modname); - type = class_search_type(name); } else { LCONSOLE_ERROR_MSG(0x158, "Can't load module '%s'\n", modname); } + spin_lock(&obd_types_lock); + type = __class_search_type(name); } if (type) { - spin_lock(&type->obd_type_lock); - type->typ_refcnt++; - try_module_get(type->typ_dt_ops->owner); - spin_unlock(&type->obd_type_lock); + if (try_module_get(type->typ_dt_ops->owner)) + type->typ_refcnt++; + else + type = NULL; } + spin_unlock(&obd_types_lock); return type; } void class_put_type(struct obd_type *type) { LASSERT(type); - spin_lock(&type->obd_type_lock); + spin_lock(&obd_types_lock); + LASSERT(type->typ_refcnt > 0); type->typ_refcnt--; module_put(type->typ_dt_ops->owner); - spin_unlock(&type->obd_type_lock); + spin_unlock(&obd_types_lock); } static void class_sysfs_release(struct kobject *kobj) @@ -206,7 +213,6 @@ int class_register_type(struct obd_ops *dt_ops, struct md_ops *md_ops, if (md_ops) *type->typ_md_ops = *md_ops; strcpy(type->typ_name, name); - spin_lock_init(&type->obd_type_lock); type->typ_debugfs_entry = debugfs_create_dir(type->typ_name, debugfs_lustre_root);
Safe module loading requires that we try_module_get() in a context where the module cannot be unloaded, typically prodected by a spinlock that module-unload has to take. This doesn't currently happen in class_get_type(). There is a per-type spinlock, but it is almost entirely unused, and cannot be used to protect the module from being unloaded. So discard ->obd_type_lock, and ensure that __class_search_type() and try_module_get() are both called while obd_types_lock is held - this prevent class_unregister_type() from completing (so the 'type' won't get freed. That is always called from a module-unload function - if it has got that far, try_module_get() will fail. So also check the return status of try_module_get(). Signed-off-by: NeilBrown <neilb@suse.com> --- drivers/staging/lustre/lustre/include/obd.h | 1 - drivers/staging/lustre/lustre/obdclass/genops.c | 24 ++++++++++++++--------- 2 files changed, 15 insertions(+), 10 deletions(-)