wrapper/splice.c

   1 /*
   2  * wrapper/splice.c
   3  *
   4  * wrapper around splice_to_pipe. Using KALLSYMS to get its address when
   5  * available, else we need to have a kernel that exports this function to GPL
   6  * modules. The export was introduced in kernel 4.2.
   7  *
   8  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9  *
  10  * This library is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; only
  13  * version 2.1 of the License.
  14  *
  15  * This library is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with this library; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 #include <lttng-kernel-version.h>
  26
  27 #if (defined(CONFIG_KALLSYMS) \
  28         && (LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0)))
  29
  30 #include <linux/kallsyms.h>
  31 #include <linux/fs.h>
  32 #include <linux/splice.h>
  33 #include <wrapper/kallsyms.h>
  34
  35 static
  36 ssize_t (*splice_to_pipe_sym)(struct pipe_inode_info *pipe,
  37                               struct splice_pipe_desc *spd);
  38
  39 ssize_t wrapper_splice_to_pipe(struct pipe_inode_info *pipe,
  40                                struct splice_pipe_desc *spd)
  41 {
  42         if (!splice_to_pipe_sym)
  43                 splice_to_pipe_sym = (void *) kallsyms_lookup_funcptr("splice_to_pipe");
  44         if (splice_to_pipe_sym) {
  45                 return splice_to_pipe_sym(pipe, spd);
  46         } else {
  47                 printk_once(KERN_WARNING "LTTng: splice_to_pipe symbol lookup failed.\n");
  48                 return -ENOSYS;
  49         }
  50 }
  51
  52 #else
  53
  54 #include <linux/fs.h>
  55 #include <linux/splice.h>
  56
  57 ssize_t wrapper_splice_to_pipe(struct pipe_inode_info *pipe,
  58                                struct splice_pipe_desc *spd)
  59 {
  60         return splice_to_pipe(pipe, spd);
  61 }
  62
  63 #endif