wrapper/poll.c

   1 /*
   2  * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
   3  *
   4  * wrapper around poll __pollwait and poll_get_entry. Using KALLSYMS to get its
   5  * address when available, else we need to have a kernel that exports this
   6  * function to GPL modules.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #ifdef CONFIG_KALLSYMS
  12
  13 #include <linux/kallsyms.h>
  14 #include <linux/poll.h>
  15
  16 struct poll_table_entry;
  17 struct splice_pipe_desc;
  18
  19 static
  20 void (*__pollwait_sym)(struct file *filp, wait_queue_head_t *wait_address,
  21                 poll_table *p);
  22 static
  23 struct poll_table_entry *(*poll_get_entry_sym)(struct poll_wqueues *p);
  24
  25 void wrapper_pollwait_exclusive(struct file *filp,
  26                          wait_queue_head_t *wait_address,
  27                          poll_table *p)
  28
  29 {
  30         struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);
  31         struct poll_table_entry *entry;
  32
  33         if (!poll_get_entry_sym)
  34                 poll_get_entry_sym = (void *) kallsyms_lookup_name("poll_get_entry");
  35         if (!poll_get_entry_sym) {
  36                 printk(KERN_WARNING "LTTng: poll_get_entry_sym symbol lookup failed.\n");
  37                 return;
  38         }
  39         entry = poll_get_entry_sym(pwq);
  40
  41         if (!__pollwait_sym)
  42                 __pollwait_sym = (void *) kallsyms_lookup_name("__pollwait");
  43         if (!__pollwait_sym) {
  44                 printk(KERN_WARNING "LTTng: __pollwait symbol lookup failed.\n");
  45                 return;
  46         }
  47         return __pollwait_sym(filp, wait_address, p);
  48 }
  49
  50 #else
  51
  52 #include <linux/poll.h>
  53
  54 ssize_t wrapper_pollwait_exclusive(struct file *filp,
  55                         wait_queue_head_t *wait_address,
  56                         poll_table *p)
  57 {
  58         return pollwait_exclusive(filp, wait_address, p);
  59 }
  60
  61 #endif