On 22.05.2012 18:29, Myklebust, Trond wrote:
On Tue, 2012-05-22 at 16:40 +0400, Stanislav Kinsbursky wrote:
Client have to be initialized prior to adding it to per-net clients list,
because otherwise there are races, shown below:
CPU#0 CPU#1
_____ _____
nfs_get_client
nfs_alloc_client
list_add(..., nfs_client_list)
rpc_fill_super
rpc_pipefs_event
nfs_get_client_for_event
__rpc_pipefs_event
(clp->cl_rpcclient is uninitialized)
BUG()
init_client
clp->cl_rpcclient = ...
Why not simply change nfs_get_client_for_event() so that it doesn't
touch nfs_clients that have clp->cl_cons_state!=NFS_CS_READY?
That should ensure that it doesn't touch nfs_clients that failed to
initialise and/or are still in the process of being initialised.
It looks like in this case we will have another races:
CPU#0 CPU#1
_____ _____
nfs4_init_client
nfs_idmap_new
nfs_idmap_register
rpc_get_sb_net (fail - no pipefs)
rpc_fill_super
rpc_pipefs_event
nfs_get_client_for_event
(skip client - NFS_CS_READY is not set)
nfs_mark_client_ready(NFS_CS_READY)
And we are having client without idmap pipe...
Cheers
Trond
--
Best regards,
Stanislav Kinsbursky
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