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isert: Fix race between target_del_all() and iscsit_unregister_transport()

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When iscsi-scstd exits for some reason, release on character device ctr_name is called.
The release function of this character device calls target_del_all().
In order to avoid a scenario where isert-scst is being removed at the same time
as iscsi-scstd is closing ctr_name device, increment reference count in portal creation
so that the module will not disappear before target_del_all() finishes using it.

This scenario is only relevant for isert-scst, as iscsi-scst will have positive reference count
at least untill target_del_all() finishes due to __fput() being called only after the release
method of the character device has returned.

Signed-off-by: Yan Burman <yanb@mellanox.com>

git-svn-id: http://svn.code.sf.net/p/scst/svn/branches/iser@5327 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Yan Burman
2014-03-13 14:48:33 +00:00
parent 0d0d959485
commit e900e70a06
1 changed files with 21 additions and 4 deletions
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25
iscsi-scst/kernel/isert-scst/iser_rdma.c
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@@ -1393,10 +1393,17 @@ struct isert_portal *isert_portal_create(void)
struct rdma_cm_id *cm_id;
int err;
if (!try_module_get(THIS_MODULE)) {
pr_err("Unable increment module reference\n");
portal = ERR_PTR(-EINVAL);
goto out;
}
portal = kzalloc(sizeof(*portal), GFP_KERNEL);
if (!portal) {
if (unlikely(!portal)) {
pr_err("Unable to allocate struct portal\n");
return ERR_PTR(-ENOMEM);
portal = ERR_PTR(-ENOMEM);
goto err_alloc;
}
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 0, 0) && !defined(RHEL_MAJOR)
@@ -1405,10 +1412,10 @@ struct isert_portal *isert_portal_create(void)
cm_id = rdma_create_id(isert_cm_evt_handler, portal, RDMA_PS_TCP,
IB_QPT_RC);
#endif
if (IS_ERR(cm_id)) {
if (unlikely(IS_ERR(cm_id))) {
err = PTR_ERR(cm_id);
pr_err("Failed to create rdma id, err:%d\n", err);
return ERR_PTR(err);
goto create_id_err;
}
portal->cm_id = cm_id;
@@ -1420,7 +1427,15 @@ struct isert_portal *isert_portal_create(void)
#endif
pr_info("Created iser portal cm_id:%p\n", cm_id);
out:
return portal;
create_id_err:
kfree(portal);
portal = ERR_PTR(err);
err_alloc:
module_put(THIS_MODULE);
goto out;
}
int isert_portal_listen(struct isert_portal *portal,
@@ -1495,6 +1510,8 @@ void isert_portal_release(struct isert_portal *portal)
mutex_unlock(&dev_list_mutex);
isert_portal_list_remove(portal);
module_put(THIS_MODULE);
}
struct isert_portal *isert_portal_start(struct sockaddr *sa, size_t addr_len)