- rcu_read_lock();
- fdt = files_fdtable(current->files);
- max_fds = fdt->max_fds;
- rcu_read_unlock();
- if (n < 0 || n > max_fds)
- goto out_nofds;
-
- /*
- * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
- * since we used fdset we need to allocate memory in units of
- * long-words.
- */
- ret = -ENOMEM;
- size = FDS_BYTES(n);
- bits = kmalloc(6 * size, GFP_KERNEL);
- if (!bits)
- goto out_nofds;
- fds.in = (unsigned long *) bits;
- fds.out = (unsigned long *) (bits + size);
- fds.ex = (unsigned long *) (bits + 2*size);
- fds.res_in = (unsigned long *) (bits + 3*size);
- fds.res_out = (unsigned long *) (bits + 4*size);
- fds.res_ex = (unsigned long *) (bits + 5*size);
-
- if ((ret = get_fd_set(n, inp->fds_bits, fds.in)) ||
- (ret = get_fd_set(n, outp->fds_bits, fds.out)) ||
- (ret = get_fd_set(n, exp->fds_bits, fds.ex)))
- goto out;
- zero_fd_set(n, fds.res_in);
- zero_fd_set(n, fds.res_out);
- zero_fd_set(n, fds.res_ex);
-
- ret = do_select(n, &fds, &timeout);
-