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>

diff --git a/fs/file.c b/fs/file.c
index e6e418122587f04ed62080b7164f98a59719a1ba..15750b80e3ceaedf00ae8258ca6ece0684381428 100644 (file)
--- a/fs/file.c
+++ b/fs/file.c
@@ -519,6 +519,12 @@ struct files_struct init_files = {
        .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.
  */

diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index fb7dacae052274fb17089f0ace563b3933f27572..45052aa814c899e4c88bb2d66ab8f9dc58a42d2b 100644 (file)
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -95,6 +95,7 @@ struct task_struct;
 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 *);

diff --git a/kernel/exit.c b/kernel/exit.c
index 20dfc7617c2e07f46dfa9fc551cc9bd51ffbe508..095113321318e43d70183f14af27ae6e5ce41320 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -457,9 +457,7 @@ void daemonize(const char *name, ...)
        /* 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();
 }