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SUNRPC: Use RCU to dereference the rpc_clnt.cl_xprt field

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A migration event will replace the rpc_xprt used by an rpc_clnt.  To
ensure this can be done safely, all references to cl_xprt must now use
a form of rcu_dereference().

Special care is taken with rpc_peeraddr2str(), which returns a pointer
to memory whose lifetime is the same as the rpc_xprt.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
[ cel: fix lockdep splats and layering violations ]
[ cel: forward ported to 3.4 ]
[ cel: remove rpc_max_reqs(), add rpc_net_ns() ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust
2012-03-01 17:00:56 -05:00
parent a3ca5651cb
commit 2446ab6070
13 changed files with 175 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files

110
net/sunrpc/clnt.c
View File

@@ -31,6 +31,7 @@
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/un.h>
#include <linux/rcupdate.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
@@ -81,7 +82,8 @@ static int rpc_ping(struct rpc_clnt *clnt);
static void rpc_register_client(struct rpc_clnt *clnt)
{
struct sunrpc_net *sn = net_generic(clnt->cl_xprt->xprt_net, sunrpc_net_id);
struct net *net = rpc_net_ns(clnt);
struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
spin_lock(&sn->rpc_client_lock);
list_add(&clnt->cl_clients, &sn->all_clients);
@@ -90,7 +92,8 @@ static void rpc_register_client(struct rpc_clnt *clnt)
static void rpc_unregister_client(struct rpc_clnt *clnt)
{
struct sunrpc_net *sn = net_generic(clnt->cl_xprt->xprt_net, sunrpc_net_id);
struct net *net = rpc_net_ns(clnt);
struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
spin_lock(&sn->rpc_client_lock);
list_del(&clnt->cl_clients);
@@ -109,12 +112,13 @@ static void __rpc_clnt_remove_pipedir(struct rpc_clnt *clnt)
static void rpc_clnt_remove_pipedir(struct rpc_clnt *clnt)
{
struct net *net = rpc_net_ns(clnt);
struct super_block *pipefs_sb;
pipefs_sb = rpc_get_sb_net(clnt->cl_xprt->xprt_net);
pipefs_sb = rpc_get_sb_net(net);
if (pipefs_sb) {
__rpc_clnt_remove_pipedir(clnt);
rpc_put_sb_net(clnt->cl_xprt->xprt_net);
rpc_put_sb_net(net);
}
}
@@ -155,17 +159,18 @@ static struct dentry *rpc_setup_pipedir_sb(struct super_block *sb,
static int
rpc_setup_pipedir(struct rpc_clnt *clnt, const char *dir_name)
{
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(clnt->cl_xprt->xprt_net);
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(clnt->cl_xprt->xprt_net);
rpc_put_sb_net(net);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
clnt->cl_dentry = dentry;
@@ -295,7 +300,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru
if (clnt->cl_server == NULL)
goto out_no_server;
clnt->cl_xprt = xprt;
rcu_assign_pointer(clnt->cl_xprt, xprt);
clnt->cl_procinfo = version->procs;
clnt->cl_maxproc = version->nrprocs;
clnt->cl_protname = program->name;
@@ -310,7 +315,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru
INIT_LIST_HEAD(&clnt->cl_tasks);
spin_lock_init(&clnt->cl_lock);
if (!xprt_bound(clnt->cl_xprt))
if (!xprt_bound(xprt))
clnt->cl_autobind = 1;
clnt->cl_timeout = xprt->timeout;
@@ -477,6 +482,7 @@ struct rpc_clnt *
rpc_clone_client(struct rpc_clnt *clnt)
{
struct rpc_clnt *new;
struct rpc_xprt *xprt;
int err = -ENOMEM;
new = kmemdup(clnt, sizeof(*new), GFP_KERNEL);
@@ -499,18 +505,25 @@ rpc_clone_client(struct rpc_clnt *clnt)
if (new->cl_principal == NULL)
goto out_no_principal;
}
rcu_read_lock();
xprt = xprt_get(rcu_dereference(clnt->cl_xprt));
rcu_read_unlock();
if (xprt == NULL)
goto out_no_transport;
rcu_assign_pointer(new->cl_xprt, xprt);
atomic_set(&new->cl_count, 1);
err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name);
if (err != 0)
goto out_no_path;
if (new->cl_auth)
atomic_inc(&new->cl_auth->au_count);
xprt_get(clnt->cl_xprt);
atomic_inc(&clnt->cl_count);
rpc_register_client(new);
rpciod_up();
return new;
out_no_path:
xprt_put(xprt);
out_no_transport:
kfree(new->cl_principal);
out_no_principal:
rpc_free_iostats(new->cl_metrics);
@@ -590,7 +603,7 @@ rpc_free_client(struct rpc_clnt *clnt)
rpc_free_iostats(clnt->cl_metrics);
kfree(clnt->cl_principal);
clnt->cl_metrics = NULL;
xprt_put(clnt->cl_xprt);
xprt_put(rcu_dereference_raw(clnt->cl_xprt));
rpciod_down();
kfree(clnt);
}
@@ -879,13 +892,18 @@ EXPORT_SYMBOL_GPL(rpc_call_start);
size_t rpc_peeraddr(struct rpc_clnt *clnt, struct sockaddr *buf, size_t bufsize)
{
size_t bytes;
struct rpc_xprt *xprt = clnt->cl_xprt;
struct rpc_xprt *xprt;
bytes = sizeof(xprt->addr);
rcu_read_lock();
xprt = rcu_dereference(clnt->cl_xprt);
bytes = xprt->addrlen;
if (bytes > bufsize)
bytes = bufsize;
memcpy(buf, &clnt->cl_xprt->addr, bytes);
return xprt->addrlen;
memcpy(buf, &xprt->addr, bytes);
rcu_read_unlock();
return bytes;
}
EXPORT_SYMBOL_GPL(rpc_peeraddr);
@@ -894,11 +912,16 @@ EXPORT_SYMBOL_GPL(rpc_peeraddr);
* @clnt: RPC client structure
* @format: address format
*
* NB: the lifetime of the memory referenced by the returned pointer is
* the same as the rpc_xprt itself. As long as the caller uses this
* pointer, it must hold the RCU read lock.
*/
const char *rpc_peeraddr2str(struct rpc_clnt *clnt,
enum rpc_display_format_t format)
{
struct rpc_xprt *xprt = clnt->cl_xprt;
struct rpc_xprt *xprt;
xprt = rcu_dereference(clnt->cl_xprt);
if (xprt->address_strings[format] != NULL)
return xprt->address_strings[format];
@@ -910,14 +933,51 @@ EXPORT_SYMBOL_GPL(rpc_peeraddr2str);
void
rpc_setbufsize(struct rpc_clnt *clnt, unsigned int sndsize, unsigned int rcvsize)
{
struct rpc_xprt *xprt = clnt->cl_xprt;
struct rpc_xprt *xprt;
rcu_read_lock();
xprt = rcu_dereference(clnt->cl_xprt);
if (xprt->ops->set_buffer_size)
xprt->ops->set_buffer_size(xprt, sndsize, rcvsize);
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(rpc_setbufsize);
/*
* Return size of largest payload RPC client can support, in bytes
/**
* rpc_protocol - Get transport protocol number for an RPC client
* @clnt: RPC client to query
*
*/
int rpc_protocol(struct rpc_clnt *clnt)
{
int protocol;
rcu_read_lock();
protocol = rcu_dereference(clnt->cl_xprt)->prot;
rcu_read_unlock();
return protocol;
}
EXPORT_SYMBOL_GPL(rpc_protocol);
/**
* rpc_net_ns - Get the network namespace for this RPC client
* @clnt: RPC client to query
*
*/
struct net *rpc_net_ns(struct rpc_clnt *clnt)
{
struct net *ret;
rcu_read_lock();
ret = rcu_dereference(clnt->cl_xprt)->xprt_net;
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(rpc_net_ns);
/**
* rpc_max_payload - Get maximum payload size for a transport, in bytes
* @clnt: RPC client to query
*
* For stream transports, this is one RPC record fragment (see RFC
* 1831), as we don't support multi-record requests yet. For datagram
@@ -926,7 +986,12 @@ EXPORT_SYMBOL_GPL(rpc_setbufsize);
*/
size_t rpc_max_payload(struct rpc_clnt *clnt)
{
return clnt->cl_xprt->max_payload;
size_t ret;
rcu_read_lock();
ret = rcu_dereference(clnt->cl_xprt)->max_payload;
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(rpc_max_payload);
@@ -937,8 +1002,11 @@ EXPORT_SYMBOL_GPL(rpc_max_payload);
*/
void rpc_force_rebind(struct rpc_clnt *clnt)
{
if (clnt->cl_autobind)
xprt_clear_bound(clnt->cl_xprt);
if (clnt->cl_autobind) {
rcu_read_lock();
xprt_clear_bound(rcu_dereference(clnt->cl_xprt));
rcu_read_unlock();
}
}
EXPORT_SYMBOL_GPL(rpc_force_rebind);