sunrpc: don't wait for write before allowing reads from use-gss-proxy file

It doesn't make much sense to make reads from this procfile hang. As
far as I can tell, only gssproxy itself will open this file and it
never reads from it. Change it to just give the present setting of
sn->use_gss_proxy without waiting for anything.

Note that we do not want to call use_gss_proxy() in this codepath
since an inopportune read of this file could cause it to be disabled
prematurely.

Cc: stable@vger.kernel.org
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

3 files changed, 2 insertions, 34 deletions

diff --git a/net/sunrpc/auth_gss/gss_rpc_upcall.c b/net/sunrpc/auth_gss/gss_rpc_upcall.c
index 458f85e9b0ba..abbb7dcd1689 100644
--- a/net/sunrpc/auth_gss/gss_rpc_upcall.c
+++ b/net/sunrpc/auth_gss/gss_rpc_upcall.c
@@ -137,7 +137,6 @@ void init_gssp_clnt(struct sunrpc_net *sn)
 {
         mutex_init(&sn->gssp_lock);
         sn->gssp_clnt = NULL;
-        init_waitqueue_head(&sn->gssp_wq);
 }
 
 int set_gssp_clnt(struct net *net)
@@ -154,7 +153,6 @@ int set_gssp_clnt(struct net *net)
                 sn->gssp_clnt = clnt;
         }
         mutex_unlock(&sn->gssp_lock);
-        wake_up(&sn->gssp_wq);
         return ret;
 }
 
diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 008cdade5aae..1b94a9c8a242 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1295,34 +1295,9 @@ static int set_gss_proxy(struct net *net, int type)
         else
                 ret = -EBUSY;
         spin_unlock(&use_gssp_lock);
-        wake_up(&sn->gssp_wq);
         return ret;
 }
 
-static inline bool gssp_ready(struct sunrpc_net *sn)
-{
-        switch (sn->use_gss_proxy) {
-                case -1:
-                        return false;
-                case 0:
-                        return true;
-                case 1:
-                        return sn->gssp_clnt;
-        }
-        WARN_ON_ONCE(1);
-        return false;
-}
-
-static int wait_for_gss_proxy(struct net *net, struct file *file)
-{
-        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
-
-        if (file->f_flags & O_NONBLOCK && !gssp_ready(sn))
-                return -EAGAIN;
-        return wait_event_interruptible(sn->gssp_wq, gssp_ready(sn));
-}
-
-
 static ssize_t write_gssp(struct file *file, const char __user *buf,
                          size_t count, loff_t *ppos)
 {
@@ -1355,16 +1330,12 @@ static ssize_t read_gssp(struct file *file, char __user *buf,
                          size_t count, loff_t *ppos)
 {
         struct net *net = PDE_DATA(file_inode(file));
+        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
         unsigned long p = *ppos;
         char tbuf[10];
         size_t len;
-        int ret;
-
-        ret = wait_for_gss_proxy(net, file);
-        if (ret)
-                return ret;
 
-        snprintf(tbuf, sizeof(tbuf), "%d\n", use_gss_proxy(net));
+        snprintf(tbuf, sizeof(tbuf), "%d\n", sn->use_gss_proxy);
         len = strlen(tbuf);
         if (p >= len)
                 return 0;
diff --git a/net/sunrpc/netns.h b/net/sunrpc/netns.h
index 779742cfc1ff..3a260e47fad2 100644
--- a/net/sunrpc/netns.h
+++ b/net/sunrpc/netns.h
@@ -26,7 +26,6 @@ struct sunrpc_net {
         unsigned int rpcb_is_af_local : 1;
 
         struct mutex gssp_lock;
-        wait_queue_head_t gssp_wq;
         struct rpc_clnt *gssp_clnt;
         int use_gss_proxy;
         int pipe_version;