new helper: iterate_fd()

iterates through the opened files in given descriptor table,
calling a supplied function; we stop once non-zero is returned.
Callback gets struct file *, descriptor number and const void *
argument passed to iterator.  It is called with files->file_lock
held, so it is not allowed to block.

tty_io, netprio_cgroup and selinux flush_unauthorized_files()
converted to its use.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 12 insertions, 26 deletions

diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index c75e3f9d060f..5ffd084c6a83 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -272,38 +272,24 @@ out_free_devname:
         return ret;
 }
 
+static int update_netprio(const void *v, struct file *file, unsigned n)
+{
+        int err;
+        struct socket *sock = sock_from_file(file, &err);
+        if (sock)
+                sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
+        return 0;
+}
+
 void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 {
         struct task_struct *p;
+        void *v;
 
         cgroup_taskset_for_each(p, cgrp, tset) {
-                unsigned int fd;
-                struct fdtable *fdt;
-                struct files_struct *files;
-
                 task_lock(p);
-                files = p->files;
-                if (!files) {
-                        task_unlock(p);
-                        continue;
-                }
-
-                spin_lock(&files->file_lock);
-                fdt = files_fdtable(files);
-                for (fd = 0; fd < fdt->max_fds; fd++) {
-                        struct file *file;
-                        struct socket *sock;
-                        int err;
-
-                        file = fcheck_files(files, fd);
-                        if (!file)
-                                continue;
-
-                        sock = sock_from_file(file, &err);
-                        if (sock)
-                                sock_update_netprioidx(sock->sk, p);
-                }
-                spin_unlock(&files->file_lock);
+                v = (void *)(unsigned long)task_netprioidx(p);
+                iterate_fd(p->files, 0, update_netprio, v);
                 task_unlock(p);
         }
 }