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NFSv4: Remove BUG_ON() and ACCESS_ONCE() calls in the idmapper 

The use of ACCESS_ONCE() is wrong, since the various routines that set/clear
idmap->idmap_key_cons should be strictly ordered w.r.t. each other, and
the idmap->idmap_mutex ensures that only one thread at a time may be in
an upcall situation.

Also replace the BUG_ON()s with WARN_ON_ONCE() where appropriate.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2012-09-28 12:03:09 -04:00
parent 62d98c9354
commit 0e24d849c4
1 changed files with 7 additions and 6 deletions
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13
fs/nfs/idmap.c
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@ -465,8 +465,6 @@ nfs_idmap_new(struct nfs_client *clp)
struct rpc_pipe *pipe;
int error;
BUG_ON(clp->cl_idmap != NULL);
idmap = kzalloc(sizeof(*idmap), GFP_KERNEL);
if (idmap == NULL)
return -ENOMEM;
@ -510,7 +508,6 @@ static int __rpc_pipefs_event(struct nfs_client *clp, unsigned long event,
switch (event) {
case RPC_PIPEFS_MOUNT:
BUG_ON(clp->cl_rpcclient->cl_dentry == NULL);
err = __nfs_idmap_register(clp->cl_rpcclient->cl_dentry,
clp->cl_idmap,
clp->cl_idmap->idmap_pipe);
@ -689,7 +686,11 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
if (ret < 0)
goto out2;
BUG_ON(idmap->idmap_key_cons != NULL);
if (idmap->idmap_key_cons != NULL) {
WARN_ON_ONCE(1);
ret = -EAGAIN;
goto out2;
}
idmap->idmap_key_cons = cons;
ret = rpc_queue_upcall(idmap->idmap_pipe, msg);
@ -746,7 +747,7 @@ idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
* will have been woken up and someone else may now have used
* idmap_key_cons - so after this point we may no longer touch it.
*/
cons = ACCESS_ONCE(idmap->idmap_key_cons);
cons = idmap->idmap_key_cons;
idmap->idmap_key_cons = NULL;
if (mlen != sizeof(im)) {
@ -790,7 +791,7 @@ idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
struct idmap *idmap = data->idmap;
struct key_construction *cons;
if (msg->errno) {
cons = ACCESS_ONCE(idmap->idmap_key_cons);
cons = idmap->idmap_key_cons;
idmap->idmap_key_cons = NULL;
complete_request_key(cons, msg->errno);
}