Commit 0e24d849 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 62d98c93

fs/nfs/idmap.c

+7 −6
Original line number Diff line number Diff line
@@ -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);

	}

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