--- /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/miscdevice.h>
+#include <linux/module.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/syscalls.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 struct file *
+fget_from_files(struct files_struct *files, unsigned fd)
+{
+ struct file *file;
+
+ rcu_read_lock();
+ file = fcheck_files(files, fd);
+ if (file) {
+ if (file->f_mode & FMODE_PATH ||
+ !atomic_long_inc_not_zero(&file->f_count)) {
+
+ file = NULL;
+ }
+ }
+ rcu_read_unlock();
+
+ return file;
+}
+
+static long
+eventfd_link_ioctl_copy2(unsigned long arg)
+{
+ void __user *argp = (void __user *) arg;
+ struct task_struct *task_target = NULL;
+ struct file *file;
+ struct files_struct *files;
+ struct eventfd_copy2 eventfd_copy2;
+ long ret = -EFAULT;
+
+ if (copy_from_user(&eventfd_copy2, argp, sizeof(struct eventfd_copy2)))
+ goto out;
+
+ /*
+ * Find the task struct for the target pid
+ */
+ ret = -ESRCH;
+
+ task_target =
+ get_pid_task(find_vpid(eventfd_copy2.pid), PIDTYPE_PID);
+ if (task_target == NULL) {
+ pr_info("Unable to find pid %d\n", eventfd_copy2.pid);
+ goto out;
+ }
+
+ ret = -ESTALE;
+ files = get_files_struct(task_target);
+ if (files == NULL) {
+ pr_info("Failed to get target files struct\n");
+ goto out_task;
+ }
+
+ ret = -EBADF;
+ file = fget_from_files(files, eventfd_copy2.fd);
+ put_files_struct(files);
+
+ if (file == NULL) {
+ pr_info("Failed to get fd %d from target\n", eventfd_copy2.fd);
+ goto out_task;
+ }
+
+ /*
+ * Install the file struct from the target process into the
+ * newly allocated file desciptor of the source process.
+ */
+ ret = get_unused_fd_flags(eventfd_copy2.flags);
+ if (ret < 0) {
+ fput(file);
+ goto out_task;
+ }
+ fd_install(ret, file);
+
+out_task:
+ put_task_struct(task_target);
+out:
+ return ret;
+}
+
+static long
+eventfd_link_ioctl_copy(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;
+ long ret = -EFAULT;
+
+ if (copy_from_user(&eventfd_copy, argp, sizeof(struct eventfd_copy)))
+ goto out;
+
+ /*
+ * Find the task struct for the target pid
+ */
+ ret = -ESRCH;
+
+ task_target =
+ get_pid_task(find_vpid(eventfd_copy.target_pid), PIDTYPE_PID);
+ if (task_target == NULL) {
+ pr_info("Unable to find pid %d\n", eventfd_copy.target_pid);
+ goto out;
+ }
+
+ ret = -ESTALE;
+ files = get_files_struct(current);
+ if (files == NULL) {
+ pr_info("Failed to get current files struct\n");
+ goto out_task;
+ }
+
+ ret = -EBADF;
+ file = fget_from_files(files, eventfd_copy.source_fd);
+
+ if (file == NULL) {
+ pr_info("Failed to get fd %d from source\n",
+ eventfd_copy.source_fd);
+ put_files_struct(files);
+ goto out_task;
+ }
+
+ /*
+ * Release the existing eventfd in the source process
+ */
+ spin_lock(&files->file_lock);
+ fput(file);
+ filp_close(file, files);
+ fdt = files_fdtable(files);
+ fdt->fd[eventfd_copy.source_fd] = NULL;
+ spin_unlock(&files->file_lock);
+
+ put_files_struct(files);
+
+ /*
+ * Find the file struct associated with the target fd.
+ */
+
+ ret = -ESTALE;
+ files = get_files_struct(task_target);
+ if (files == NULL) {
+ pr_info("Failed to get target files struct\n");
+ goto out_task;
+ }
+
+ ret = -EBADF;
+ file = fget_from_files(files, eventfd_copy.target_fd);
+ put_files_struct(files);
+
+ if (file == NULL) {
+ pr_info("Failed to get fd %d from target\n",
+ eventfd_copy.target_fd);
+ goto out_task;
+ }
+
+ /*
+ * Install the file struct from the target process into the
+ * file desciptor of the source process,
+ */
+
+ fd_install(eventfd_copy.source_fd, file);
+ ret = 0;
+
+out_task:
+ put_task_struct(task_target);
+out:
+ return ret;
+}
+
+static long
+eventfd_link_ioctl(struct file *f, unsigned int ioctl, unsigned long arg)
+{
+ long ret = -ENOIOCTLCMD;
+
+ switch (ioctl) {
+ case EVENTFD_COPY:
+ ret = eventfd_link_ioctl_copy(arg);
+ break;
+ case EVENTFD_COPY2:
+ ret = eventfd_link_ioctl_copy2(arg);
+ break;
+ }
+
+ return ret;
+}
+
+static const struct file_operations eventfd_link_fops = {
+ .owner = THIS_MODULE,
+ .unlocked_ioctl = eventfd_link_ioctl,
+};
+
+
+static struct miscdevice eventfd_link_misc = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .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");
Code Review / deb_dpdk.git / blobdiff