@@ -624,14 +624,16 @@ EXPORT_SYMBOL_GPL(rpc_shutdown_client);
/*
* Free an RPC client
*/
-static void
+static struct rpc_clnt *
rpc_free_client(struct rpc_clnt *clnt)
{
+ struct rpc_clnt *parent = NULL;
+
dprintk_rcu("RPC: destroying %s client for %s\n",
clnt->cl_protname,
rcu_dereference(clnt->cl_xprt)->servername);
if (clnt->cl_parent != clnt)
- rpc_release_client(clnt->cl_parent);
+ parent = clnt->cl_parent;
rpc_clnt_remove_pipedir(clnt);
rpc_unregister_client(clnt);
rpc_free_iostats(clnt->cl_metrics);
@@ -640,18 +642,17 @@ rpc_free_client(struct rpc_clnt *clnt)
xprt_put(rcu_dereference_raw(clnt->cl_xprt));
rpciod_down();
kfree(clnt);
+ return parent;
}
/*
* Free an RPC client
*/
-static void
+static struct rpc_clnt *
rpc_free_auth(struct rpc_clnt *clnt)
{
- if (clnt->cl_auth == NULL) {
- rpc_free_client(clnt);
- return;
- }
+ if (clnt->cl_auth == NULL)
+ return rpc_free_client(clnt);
/*
* Note: RPCSEC_GSS may need to send NULL RPC calls in order to
@@ -662,7 +663,8 @@ rpc_free_auth(struct rpc_clnt *clnt)
rpcauth_release(clnt->cl_auth);
clnt->cl_auth = NULL;
if (atomic_dec_and_test(&clnt->cl_count))
- rpc_free_client(clnt);
+ return rpc_free_client(clnt);
+ return NULL;
}
/*
@@ -673,10 +675,13 @@ rpc_release_client(struct rpc_clnt *clnt)
{
dprintk("RPC: rpc_release_client(%p)\n", clnt);
- if (list_empty(&clnt->cl_tasks))
- wake_up(&destroy_wait);
- if (atomic_dec_and_test(&clnt->cl_count))
- rpc_free_auth(clnt);
+ do {
+ if (list_empty(&clnt->cl_tasks))
+ wake_up(&destroy_wait);
+ if (!atomic_dec_and_test(&clnt->cl_count))
+ break;
+ clnt = rpc_free_auth(clnt);
+ } while (clnt != NULL);
}
/**
This is a note to let you know that I have just added a patch titled SUNRPC: Avoid deep recursion in rpc_release_client to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.14. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From f3ae133df1082183df18370d24c6102bcfee4917 Mon Sep 17 00:00:00 2001 From: Trond Myklebust <Trond.Myklebust@netapp.com> Date: Tue, 12 Nov 2013 17:24:36 -0500 Subject: SUNRPC: Avoid deep recursion in rpc_release_client commit d07ba8422f1e58be94cc98a1f475946dc1b89f1b upstream. In cases where an rpc client has a parent hierarchy, then rpc_free_client may end up calling rpc_release_client() on the parent, thus recursing back into rpc_free_client. If the hierarchy is deep enough, then we can get into situations where the stack simply overflows. The fix is to have rpc_release_client() loop so that it can take care of the parent rpc client hierarchy without needing to recurse. Reported-by: Jeff Layton <jlayton@redhat.com> Reported-by: Weston Andros Adamson <dros@netapp.com> Reported-by: Bruce Fields <bfields@fieldses.org> Link: http://lkml.kernel.org/r/2C73011F-0939-434C-9E4D-13A1EB1403D7@netapp.com Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/sunrpc/clnt.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) -- 1.8.3.2