diff options
Diffstat (limited to 'lib/librte_vhost/eventfd_link/eventfd_link.c')
| -rw-r--r-- | lib/librte_vhost/eventfd_link/eventfd_link.c | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/lib/librte_vhost/eventfd_link/eventfd_link.c b/lib/librte_vhost/eventfd_link/eventfd_link.c new file mode 100644 index 00000000..4b05b5a8 --- /dev/null +++ b/lib/librte_vhost/eventfd_link/eventfd_link.c @@ -0,0 +1,277 @@ +/*- + * 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"); |