SUNRPC: Use RCU to dereference the rpc_clnt.cl_xprt field
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>
diff --git a/net/sunrpc/stats.c b/net/sunrpc/stats.c
index 1eb3304..bc2068e 100644
--- a/net/sunrpc/stats.c
+++ b/net/sunrpc/stats.c
@@ -22,6 +22,7 @@
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/metrics.h>
+#include <linux/rcupdate.h>
#include "netns.h"
@@ -179,7 +180,7 @@
void rpc_print_iostats(struct seq_file *seq, struct rpc_clnt *clnt)
{
struct rpc_iostats *stats = clnt->cl_metrics;
- struct rpc_xprt *xprt = clnt->cl_xprt;
+ struct rpc_xprt *xprt;
unsigned int op, maxproc = clnt->cl_maxproc;
if (!stats)
@@ -189,8 +190,11 @@
seq_printf(seq, "p/v: %u/%u (%s)\n",
clnt->cl_prog, clnt->cl_vers, clnt->cl_protname);
+ rcu_read_lock();
+ xprt = rcu_dereference(clnt->cl_xprt);
if (xprt)
xprt->ops->print_stats(xprt, seq);
+ rcu_read_unlock();
seq_printf(seq, "\tper-op statistics\n");
for (op = 0; op < maxproc; op++) {