diff options
| author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2013-11-12 17:24:36 -0500 |
|---|---|---|
| committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2013-11-12 18:56:57 -0500 |
| commit | d07ba8422f1e58be94cc98a1f475946dc1b89f1b (patch) | |
| tree | e83c021ca30a8625b7a4af139c2d7bf16bbfa348 /net/sunrpc | |
| parent | a6b31d18b02ff9d7915c5898c9b5ca41a798cd73 (diff) | |
SUNRPC: Avoid deep recursion in rpc_release_client
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
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/clnt.c | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index dab09dac8fc..f09b7db2c49 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -750,14 +750,16 @@ 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_program->name, 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); @@ -766,18 +768,17 @@ rpc_free_client(struct rpc_clnt *clnt) rpciod_down(); rpc_free_clid(clnt); 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 @@ -788,7 +789,8 @@ 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; } /* @@ -799,10 +801,13 @@ 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); } EXPORT_SYMBOL_GPL(rpc_release_client); |