--- /dev/null
+/*-
+ * * GPL LICENSE SUMMARY
+ * *
+ * * Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+ * *
+ * * This program is free software; you can redistribute it and/or modify
+ * * it under the terms of version 2 of the GNU General Public License as
+ * * published by the Free Software Foundation.
+ * *
+ * * This program is distributed in the hope that it will be useful, but
+ * * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * * General Public License for more details.
+ * *
+ * * You should have received a copy of the GNU General Public License
+ * * along with this program; if not, write to the Free Software
+ * * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ * * The full GNU General Public License is included in this distribution
+ * * in the file called LICENSE.GPL.
+ * *
+ * * Contact Information:
+ * * Intel Corporation
+ * */
+
+#include <linux/eventfd.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/rcupdate.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/mmu_context.h>
+#include <linux/sched.h>
+#include <asm/mmu_context.h>
+#include <linux/fdtable.h>
+
+#include "eventfd_link.h"
+
+
+/*
+ * get_files_struct is copied from fs/file.c
+ */
+struct files_struct *
+get_files_struct (struct task_struct *task)
+{
+ struct files_struct *files;
+
+ task_lock (task);
+ files = task->files;
+ if (files)
+ atomic_inc (&files->count);
+ task_unlock (task);
+
+ return files;
+}
+
+/*
+ * put_files_struct is extracted from fs/file.c
+ */
+void
+put_files_struct (struct files_struct *files)
+{
+ if (atomic_dec_and_test (&files->count))
+ {
+ BUG ();
+ }
+}
+
+
+static long
+eventfd_link_ioctl (struct file *f, unsigned int ioctl, unsigned long arg)
+{
+ void __user *argp = (void __user *) arg;
+ struct task_struct *task_target = NULL;
+ struct file *file;
+ struct files_struct *files;
+ struct fdtable *fdt;
+ struct eventfd_copy eventfd_copy;
+
+ switch (ioctl)
+ {
+ case EVENTFD_COPY:
+ if (copy_from_user (&eventfd_copy, argp, sizeof (struct eventfd_copy)))
+ return -EFAULT;
+
+ /*
+ * Find the task struct for the target pid
+ */
+ task_target =
+ pid_task (find_vpid (eventfd_copy.target_pid), PIDTYPE_PID);
+ if (task_target == NULL)
+ {
+ printk (KERN_DEBUG "Failed to get mem ctx for target pid\n");
+ return -EFAULT;
+ }
+
+ files = get_files_struct (current);
+ if (files == NULL)
+ {
+ printk (KERN_DEBUG "Failed to get files struct\n");
+ return -EFAULT;
+ }
+
+ rcu_read_lock ();
+ file = fcheck_files (files, eventfd_copy.source_fd);
+ if (file)
+ {
+ if (file->f_mode & FMODE_PATH
+ || !atomic_long_inc_not_zero (&file->f_count))
+ file = NULL;
+ }
+ rcu_read_unlock ();
+ put_files_struct (files);
+
+ if (file == NULL)
+ {
+ printk (KERN_DEBUG "Failed to get file from source pid\n");
+ return 0;
+ }
+
+ /*
+ * Release the existing eventfd in the source process
+ */
+ spin_lock (&files->file_lock);
+ filp_close (file, files);
+ fdt = files_fdtable (files);
+ fdt->fd[eventfd_copy.source_fd] = NULL;
+ spin_unlock (&files->file_lock);
+
+ /*
+ * Find the file struct associated with the target fd.
+ */
+
+ files = get_files_struct (task_target);
+ if (files == NULL)
+ {
+ printk (KERN_DEBUG "Failed to get files struct\n");
+ return -EFAULT;
+ }
+
+ rcu_read_lock ();
+ file = fcheck_files (files, eventfd_copy.target_fd);
+ if (file)
+ {
+ if (file->f_mode & FMODE_PATH
+ || !atomic_long_inc_not_zero (&file->f_count))
+ file = NULL;
+ }
+ rcu_read_unlock ();
+ put_files_struct (files);
+
+ if (file == NULL)
+ {
+ printk (KERN_DEBUG "Failed to get file from target pid\n");
+ return 0;
+ }
+
+
+ /*
+ * Install the file struct from the target process into the
+ * file desciptor of the source process,
+ */
+
+ fd_install (eventfd_copy.source_fd, file);
+
+ return 0;
+
+ default:
+ return -ENOIOCTLCMD;
+ }
+}
+
+static const struct file_operations eventfd_link_fops = {
+ .owner = THIS_MODULE,
+ .unlocked_ioctl = eventfd_link_ioctl,
+};
+
+
+static struct miscdevice eventfd_link_misc = {
+ .name = "eventfd-link",
+ .fops = &eventfd_link_fops,
+};
+
+static int __init
+eventfd_link_init (void)
+{
+ return misc_register (&eventfd_link_misc);
+}
+
+module_init (eventfd_link_init);
+
+static void __exit
+eventfd_link_exit (void)
+{
+ misc_deregister (&eventfd_link_misc);
+}
+
+module_exit (eventfd_link_exit);
+
+MODULE_VERSION ("0.0.1");
+MODULE_LICENSE ("GPL v2");
+MODULE_AUTHOR ("Anthony Fee");
+MODULE_DESCRIPTION ("Link eventfd");
+MODULE_ALIAS ("devname:eventfd-link");
git.droids-corp.org / dpdk.git / blobdiff