commit 864bdb3b6cbd9911222543fef1cfe36f88183f44
author Al Viro <viro@zeniv.linux.org.uk> Wed Aug 22 18:42:10 2012 -0400
committer Al Viro <viro@zeniv.linux.org.uk> Wed Sep 26 21:10:00 2012 -0400
tree bd00e6293592a084ee0fe68e3acb93060f54ae68
parent 2be7fd55d44882c9818ed2d1dabc0f0abab5eeed

new helper: daemonize_descriptors()

descriptor-related parts of daemonize, done right.  As the
result we simplify the locking rules for ->files - we
hold task_lock in *all* cases when we modify ->files.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/file.c

diff --git a/fs/file.c b/fs/file.c
index e6e4181..15750b8 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -519,6 +519,12 @@
 	.file_lock	= __SPIN_LOCK_UNLOCKED(init_task.file_lock),
 };
 
+void daemonize_descriptors(void)
+{
+	atomic_inc(&init_files.count);
+	reset_files_struct(&init_files);
+}
+
 /*
  * allocate a file descriptor, mark it busy.
  */

include/linux/fdtable.h

diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index fb7daca..45052aa 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -95,6 +95,7 @@
 struct files_struct *get_files_struct(struct task_struct *);
 void put_files_struct(struct files_struct *fs);
 void reset_files_struct(struct files_struct *);
+void daemonize_descriptors(void);
 int unshare_files(struct files_struct **);
 struct files_struct *dup_fd(struct files_struct *, int *);
 void do_close_on_exec(struct files_struct *);

kernel/exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index 20dfc76..0951133 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -457,9 +457,7 @@
 	/* Become as one with the init task */
 
 	daemonize_fs_struct();
-	exit_files(current);
-	current->files = init_task.files;
-	atomic_inc(&current->files->count);
+	daemonize_descriptors();
 
 	reparent_to_kthreadd();
 }