This is a note to let you know that I've just added the patch titled
SUNRPC: fix races on PipeFS MOUNT notifications
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sunrpc-fix-races-on-pipefs-mount-notifications.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 384816051ca9125cd54750e59c780c2a2655fa4f Mon Sep 17 00:00:00 2001
From: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
Date: Mon, 24 Jun 2013 11:52:38 +0400
Subject: SUNRPC: fix races on PipeFS MOUNT notifications
From: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
commit 384816051ca9125cd54750e59c780c2a2655fa4f upstream.
Below are races, when RPC client can be created without PiepFS dentries
CPU#0 CPU#1
----------------------------- -----------------------------
rpc_new_client rpc_fill_super
rpc_setup_pipedir
mutex_lock(&sn->pipefs_sb_lock)
rpc_get_sb_net == NULL
(no per-net PipeFS superblock)
sn->pipefs_sb = sb;
notifier_call_chain(MOUNT)
(client is not in the list)
rpc_register_client
(client without pipes dentries)
To fix this patch:
1) makes PipeFS mount notification call with pipefs_sb_lock being held.
2) releases pipefs_sb_lock on new SUNRPC client creation only after
registration.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sunrpc/clnt.c | 26 +++++++++++++++-----------
net/sunrpc/rpc_pipe.c | 3 +++
2 files changed, 18 insertions(+), 11 deletions(-)
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -157,20 +157,15 @@ static struct dentry *rpc_setup_pipedir_
}
static int
-rpc_setup_pipedir(struct rpc_clnt *clnt, const char *dir_name)
+rpc_setup_pipedir(struct rpc_clnt *clnt, const char *dir_name,
+ struct super_block *pipefs_sb)
{
- struct net *net = rpc_net_ns(clnt);
- struct super_block *pipefs_sb;
struct dentry *dentry;
clnt->cl_dentry = NULL;
if (dir_name == NULL)
return 0;
- pipefs_sb = rpc_get_sb_net(net);
- if (!pipefs_sb)
- return 0;
dentry = rpc_setup_pipedir_sb(pipefs_sb, clnt, dir_name);
- rpc_put_sb_net(net);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
clnt->cl_dentry = dentry;
@@ -296,6 +291,7 @@ static struct rpc_clnt * rpc_new_client(
struct rpc_clnt *clnt = NULL;
struct rpc_auth *auth;
int err;
+ struct super_block *pipefs_sb;
/* sanity check the name before trying to print it */
dprintk("RPC: creating %s client for %s (xprt %p)\n",
@@ -354,9 +350,12 @@ static struct rpc_clnt * rpc_new_client(
atomic_set(&clnt->cl_count, 1);
- err = rpc_setup_pipedir(clnt, program->pipe_dir_name);
- if (err < 0)
- goto out_no_path;
+ pipefs_sb = rpc_get_sb_net(rpc_net_ns(clnt));
+ if (pipefs_sb) {
+ err = rpc_setup_pipedir(clnt, program->pipe_dir_name, pipefs_sb);
+ if (err)
+ goto out_no_path;
+ }
auth = rpcauth_create(args->authflavor, clnt);
if (IS_ERR(auth)) {
@@ -369,11 +368,16 @@ static struct rpc_clnt * rpc_new_client(
/* save the nodename */
rpc_clnt_set_nodename(clnt, utsname()->nodename);
rpc_register_client(clnt);
+ if (pipefs_sb)
+ rpc_put_sb_net(rpc_net_ns(clnt));
return clnt;
out_no_auth:
- rpc_clnt_remove_pipedir(clnt);
+ if (pipefs_sb)
+ __rpc_clnt_remove_pipedir(clnt);
out_no_path:
+ if (pipefs_sb)
+ rpc_put_sb_net(rpc_net_ns(clnt));
kfree(clnt->cl_principal);
out_no_principal:
rpc_free_iostats(clnt->cl_metrics);
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -1126,6 +1126,7 @@ rpc_fill_super(struct super_block *sb, v
return -ENOMEM;
dprintk("RPC: sending pipefs MOUNT notification for net %p%s\n",
net, NET_NAME(net));
+ mutex_lock(&sn->pipefs_sb_lock);
sn->pipefs_sb = sb;
err = blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
RPC_PIPEFS_MOUNT,
@@ -1133,6 +1134,7 @@ rpc_fill_super(struct super_block *sb, v
if (err)
goto err_depopulate;
sb->s_fs_info = get_net(net);
+ mutex_unlock(&sn->pipefs_sb_lock);
return 0;
err_depopulate:
@@ -1141,6 +1143,7 @@ err_depopulate:
sb);
sn->pipefs_sb = NULL;
__rpc_depopulate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF);
+ mutex_unlock(&sn->pipefs_sb_lock);
return err;
}
Patches currently in stable-queue which might be from skinsbursky@xxxxxxxxxxxxx are
queue-3.10/sunrpc-fix-races-on-pipefs-mount-notifications.patch
queue-3.10/sunrpc-fix-races-on-pipefs-umount-notifications.patch
queue-3.10/sunrpc-pipefs-mount-notification-optimization-for-dying-clients.patch
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