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NFS: Add memory barriers to the nfs_client->cl_cons_state initialisation 

Ensure that a process that uses the nfs_client->cl_cons_state test
for whether the initialisation process is finished does not read
stale data.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2012-05-23 13:26:10 -04:00
parent 4697bd5e94
commit 54ac471c83
3 changed files with 7 additions and 0 deletions
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5
fs/nfs/client.c
View File

@ -459,6 +459,8 @@ static bool nfs4_cb_match_client(const struct sockaddr *addr,
clp->cl_cons_state == NFS_CS_SESSION_INITING))
return false;
smp_rmb();
/* Match the version and minorversion */
if (clp->rpc_ops->version != 4 ||
clp->cl_minorversion != minorversion)
@ -539,6 +541,8 @@ nfs_found_client(const struct nfs_client_initdata *cl_init,
return ERR_PTR(error);
}
smp_rmb();
BUG_ON(clp->cl_cons_state != NFS_CS_READY);
dprintk("<-- %s found nfs_client %p for %s\n",
@ -597,6 +601,7 @@ nfs_get_client(const struct nfs_client_initdata *cl_init,
*/
void nfs_mark_client_ready(struct nfs_client *clp, int state)
{
smp_wmb();
clp->cl_cons_state = state;
wake_up_all(&nfs_client_active_wq);
}

1
fs/nfs/idmap.c
View File

@ -548,6 +548,7 @@ static struct nfs_client *nfs_get_client_for_event(struct net *net, int event)
/* Skip nfs_clients that failed to initialise */
if (clp->cl_cons_state < 0)
continue;
smp_rmb();
if (clp->rpc_ops != &nfs_v4_clientops)
continue;
cl_dentry = clp->cl_idmap->idmap_pipe->dentry;

1
fs/nfs/nfs4proc.c
View File

@ -5621,6 +5621,7 @@ static int nfs41_check_session_ready(struct nfs_client *clp)
}
if (clp->cl_cons_state < NFS_CS_READY)
return -EPROTONOSUPPORT;
smp_rmb();
return 0;
}