From 0e24d849c4ea777c59955b241fd3af14a1b84af5 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <Trond.Myklebust@netapp.com>
Date: Fri, 28 Sep 2012 12:03:09 -0400
Subject: [PATCH] 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>
---
fs/nfs/idmap.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index a850079467d8..79f6424aa081 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -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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