From: Anna Schumaker <Anna.Schumaker@Netapp.com>
Date: Wed, 1 Nov 2017 19:48:43 +0000 (-0400)
Subject: NFS: Avoid RCU usage in tracepoints
X-Git-Tag: v3.16.54~45
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=224cf907e79fdbf852022c665ba7cdcd074fa12f;p=linux

NFS: Avoid RCU usage in tracepoints

commit 3944369db701f075092357b511fd9f5755771585 upstream.

There isn't an obvious way to acquire and release the RCU lock during a
tracepoint, so we can't use the rpc_peeraddr2str() function here.
Instead, rely on the client's cl_hostname, which should have similar
enough information without needing an rcu_dereference().

Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
[bwh: Backported to 3.16: Drop changes in
 nfs4_inode{,_stateid}_callback_event()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/fs/nfs/nfs4trace.h b/fs/nfs/nfs4trace.h
index 1c32adbe728d..14e589195cae 100644
--- a/fs/nfs/nfs4trace.h
+++ b/fs/nfs/nfs4trace.h
@@ -201,17 +201,13 @@ DECLARE_EVENT_CLASS(nfs4_clientid_event,
 		TP_ARGS(clp, error),
 
 		TP_STRUCT__entry(
-			__string(dstaddr,
-				rpc_peeraddr2str(clp->cl_rpcclient,
-					RPC_DISPLAY_ADDR))
+			__string(dstaddr, clp->cl_hostname)
 			__field(int, error)
 		),
 
 		TP_fast_assign(
 			__entry->error = error;
-			__assign_str(dstaddr,
-				rpc_peeraddr2str(clp->cl_rpcclient,
-						RPC_DISPLAY_ADDR));
+			__assign_str(dstaddr, clp->cl_hostname);
 		),
 
 		TP_printk(