net/ipv4/tcp_zero_copy.c

   1 /*
   2  *      Support routines for TCP zero copy transmit
   3  *
   4  *      Created by Vladislav Bolkhovitin
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      version 2 as published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/skbuff.h>
  12
  13 net_get_page_callback_t net_get_page_callback __read_mostly;
  14 EXPORT_SYMBOL(net_get_page_callback);
  15
  16 net_put_page_callback_t net_put_page_callback __read_mostly;
  17 EXPORT_SYMBOL(net_put_page_callback);
  18
  19 /*
  20  * Caller of this function must ensure that at the moment when it's called
  21  * there are no pages in the system with net_priv field set to non-zero
  22  * value. Hence, this function, as well as net_get_page() and net_put_page(),
  23  * don't need any protection.
  24  */
  25 int net_set_get_put_page_callbacks(
  26         net_get_page_callback_t get_callback,
  27         net_put_page_callback_t put_callback)
  28 {
  29         int res = 0;
  30
  31         if ((net_get_page_callback != NULL) && (get_callback != NULL) &&
  32             (net_get_page_callback != get_callback)) {
  33                 res = -EBUSY;
  34                 goto out;
  35         }
  36
  37         if ((net_put_page_callback != NULL) && (put_callback != NULL) &&
  38             (net_put_page_callback != put_callback)) {
  39                 res = -EBUSY;
  40                 goto out;
  41         }
  42
  43         net_get_page_callback = get_callback;
  44         net_put_page_callback = put_callback;
  45
  46 out:
  47         return res;
  48 }
  49 EXPORT_SYMBOL(net_set_get_put_page_callbacks);