[dpdk-dev] [PATCH v3] vhost: Refactor module `eventfd_link'

[Pavel Boldin <pboldin@mirantis.com>]

Changes:
 * Remove unnecessary #include's.
 * Deindent by moving the code to an inline function.
 * Fix return codes. Use appropriate return code for each fault cause.
 * Remove copy-pasted `close_fd', call `sys_close' instead.
 * Use `get_pid_task' to correctly reference the `task_target'.

Signed-off-by: Pavel Boldin <pboldin@mirantis.com>
---
Changes since last submission:
 * Using `sys_close' to close fd.
 * Removing unnecessary #include's.

 lib/librte_vhost/eventfd_link/eventfd_link.c | 193 ++++++++++++++-------------
 1 file changed, 98 insertions(+), 95 deletions(-)

diff --git a/lib/librte_vhost/eventfd_link/eventfd_link.c b/lib/librte_vhost/eventfd_link/eventfd_link.c
index 7755dd6..d10e25f 100644
--- a/lib/librte_vhost/eventfd_link/eventfd_link.c
+++ b/lib/librte_vhost/eventfd_link/eventfd_link.c
@@ -22,18 +22,11 @@
  *   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 <linux/syscalls.h>
 
 #include "eventfd_link.h"
 
@@ -65,100 +58,110 @@ put_files_struct(struct files_struct *files)
 		BUG();
 }
 
+static struct file *
+fget_from_files(struct files_struct *files, unsigned fd)
+{
+	struct file *file;
 
-static long
-eventfd_link_ioctl(struct file *f, unsigned int ioctl, unsigned long arg)
+	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 inline long
+eventfd_link_ioctl_copy(unsigned long arg)
 {
-	void __user *argp = (void __user *) arg;
+	long ret = -EFAULT;
 	struct task_struct *task_target = NULL;
-	struct file *file;
-	struct files_struct *files;
-	struct fdtable *fdt;
+	struct file *target_file = NULL;
+	struct files_struct *target_files = NULL;
 	struct eventfd_copy eventfd_copy;
+	struct pid *pid;
+
+	if (copy_from_user(&eventfd_copy, (void __user*)arg,
+			    sizeof(struct eventfd_copy)))
+		goto out;
+
+	/*
+	 * Find the task struct for the target pid
+	 */
+	ret = -ESRCH;
+
+	pid = find_vpid(eventfd_copy.target_pid);
+	if (pid == NULL) {
+		pr_info("Unable to find pid %d\n", eventfd_copy.target_pid);
+		goto out;
+	}
+
+	task_target = get_pid_task(pid, PIDTYPE_PID);
+	if (task_target == NULL) {
+		pr_info("Failed to get task for pid %d\n",
+			eventfd_copy.target_pid);
+		goto out;
+	}
+
+	ret = sys_close(eventfd_copy.source_fd);
+	if (ret)
+		goto out_task;
+	ret = -ESTALE;
 
-	switch (ioctl) {
+	/*
+	 * Find the file struct associated with the target fd.
+	 */
+
+	target_files = get_files_struct(task_target);
+	if (target_files == NULL) {
+		pr_info("Failed to get target files struct\n");
+		goto out_task;
+	}
+
+	ret = -EBADF;
+	target_file = fget_from_files(target_files, eventfd_copy.target_fd);
+
+	if (target_file == NULL) {
+		pr_info("Failed to get file from target pid\n");
+		goto out_target_files;
+	}
+
+
+	/*
+	 * Install the file struct from the target process into the
+	 * file desciptor of the source process,
+	 */
+
+	fd_install(eventfd_copy.source_fd, target_file);
+
+	ret = 0;
+
+out_target_files:
+	put_files_struct(target_files);
+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:
-		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) {
-			pr_debug("Failed to get mem ctx for target pid\n");
-			return -EFAULT;
-		}
-
-		files = get_files_struct(current);
-		if (files == NULL) {
-			pr_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) {
-			pr_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) {
-			pr_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) {
-			pr_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;
+		ret = eventfd_link_ioctl_copy(arg);
+		break;
 	}
+
+	return ret;
 }
 
 static const struct file_operations eventfd_link_fops = {
-- 
1.9.1