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RDMA/device: Fix a race between mad_client and cm_client init 

[ Upstream commit 7a8bccd8b29c321ac181369b42b04fecf05f98e2 ]

The mad_client will be initialized in enable_device_and_get(), while the
devices_rwsem will be downgraded to a read semaphore. There is a window
that leads to the failed initialization for cm_client, since it can not
get matched mad port from ib_mad_port_list, and the matched mad port will
be added to the list after that.

    mad_client    |                       cm_client
------------------|--------------------------------------------------------
ib_register_device|
enable_device_and_get
down_write(&devices_rwsem)
xa_set_mark(&devices, DEVICE_REGISTERED)
downgrade_write(&devices_rwsem)
                  |
                  |ib_cm_init
                  |ib_register_client(&cm_client)
                  |down_read(&devices_rwsem)
                  |xa_for_each_marked (&devices, DEVICE_REGISTERED)
                  |add_client_context
                  |cm_add_one
                  |ib_register_mad_agent
                  |ib_get_mad_port
                  |__ib_get_mad_port
                  |list_for_each_entry(entry, &ib_mad_port_list, port_list)
                  |return NULL
                  |up_read(&devices_rwsem)
                  |
add_client_context|
ib_mad_init_device|
ib_mad_port_open  |
list_add_tail(&port_priv->port_list, &ib_mad_port_list)
up_read(&devices_rwsem)
                  |

Fix it by using down_write(&devices_rwsem) in ib_register_client().

Fixes: d0899892ed ("RDMA/device: Provide APIs from the core code to help unregistration")
Link: https://lore.kernel.org/r/20240203035313.98991-1-lishifeng@sangfor.com.cn
Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Shifeng Li <lishifeng@sangfor.com.cn>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Shifeng Li 2024-02-02 19:53:13 -08:00 committed by Sasha Levin
parent 522e5e4770
commit 034977c33b
1 changed files with 22 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
drivers/infiniband/core/device.c
View File

@ -1730,7 +1730,7 @@ static int assign_client_id(struct ib_client *client)
{
int ret;
down_write(&clients_rwsem);
lockdep_assert_held(&clients_rwsem);
/*
* The add/remove callbacks must be called in FIFO/LIFO order. To
* achieve this we assign client_ids so they are sorted in
@ -1739,14 +1739,11 @@ static int assign_client_id(struct ib_client *client)
client->client_id = highest_client_id;
ret = xa_insert(&clients, client->client_id, client, GFP_KERNEL);
if (ret)
goto out;
return ret;
highest_client_id++;
xa_set_mark(&clients, client->client_id, CLIENT_REGISTERED);
out:
up_write(&clients_rwsem);
return ret;
return 0;
}
static void remove_client_id(struct ib_client *client)
@ -1776,25 +1773,35 @@ int ib_register_client(struct ib_client *client)
{
struct ib_device *device;
unsigned long index;
bool need_unreg = false;
int ret;
refcount_set(&client->uses, 1);
init_completion(&client->uses_zero);
/*
* The devices_rwsem is held in write mode to ensure that a racing
* ib_register_device() sees a consisent view of clients and devices.
*/
down_write(&devices_rwsem);
down_write(&clients_rwsem);
ret = assign_client_id(client);
if (ret)
return ret;
goto out;
down_read(&devices_rwsem);
need_unreg = true;
xa_for_each_marked (&devices, index, device, DEVICE_REGISTERED) {
ret = add_client_context(device, client);
if (ret) {
up_read(&devices_rwsem);
ib_unregister_client(client);
return ret;
}
if (ret)
goto out;
}
up_read(&devices_rwsem);
return 0;
ret = 0;
out:
up_write(&clients_rwsem);
up_write(&devices_rwsem);
if (need_unreg && ret)
ib_unregister_client(client);
return ret;
}
EXPORT_SYMBOL(ib_register_client);