[PATCH 1/9] tty: move the non-file related parts of tty_release to new tty_release_struct

Rob Herring
2017-01-06T16:26:27Z

For in-kernel tty users, we need to be able to create and destroy
'struct tty' that are not associated with a file. The creation side is
fine, but tty_release() needs to be split into the file handle portion
and the struct tty portion. Introduce a new function, tty_release_struct,
to handle just the destroying of a struct tty.

Signed-off-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
drivers/tty/tty_io.c | 42 ++++++++++++++++++++++++------------------
include/linux/tty.h | 1 +
2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 734a635e7363..5ebc090ec47f 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1744,6 +1744,29 @@ static int tty_release_checks(struct tty_struct *tty, int idx)
return 0;
}

+void tty_release_struct(struct tty_struct *tty, int idx)
+{
+ /*
+ * Ask the line discipline code to release its structures
+ */
+ tty_ldisc_release(tty);
+
+ /* Wait for pending work before tty destruction commmences */
+ tty_flush_works(tty);
+
+ tty_debug_hangup(tty, "freeing structure\n");
+ /*
+ * The release_tty function takes care of the details of clearing
+ * the slots and preserving the termios structure. The tty_unlock_pair
+ * should be safe as we keep a kref while the tty is locked (so the
+ * unlock never unlocks a freed tty).
+ */
+ mutex_lock(&tty_mutex);
+ release_tty(tty, idx);
+ mutex_unlock(&tty_mutex);
+}
+EXPORT_SYMBOL_GPL(tty_release_struct);
+
/**
* tty_release - vfs callback for close
* @inode: inode of tty
@@ -1898,25 +1921,8 @@ int tty_release(struct inode *inode, struct file *filp)
return 0;

tty_debug_hangup(tty, "final close\n");
- /*
- * Ask the line discipline code to release its structures
- */
- tty_ldisc_release(tty);
-
- /* Wait for pending work before tty destruction commmences */
- tty_flush_works(tty);
-
- tty_debug_hangup(tty, "freeing structure\n");
- /*
- * The release_tty function takes care of the details of clearing
- * the slots and preserving the termios structure. The tty_unlock_pair
- * should be safe as we keep a kref while the tty is locked (so the
- * unlock never unlocks a freed tty).
- */
- mutex_lock(&tty_mutex);
- release_tty(tty, idx);
- mutex_unlock(&tty_mutex);

+ tty_release_struct(tty, idx);
return 0;
}

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 40144f382516..86c7853282b7 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -528,6 +528,7 @@ extern int tty_alloc_file(struct file *file);
extern void tty_add_file(struct tty_struct *tty, struct file *file);
extern void tty_free_file(struct file *file);
extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
+extern void tty_release_struct(struct tty_struct *tty, int idx);
extern int tty_release(struct inode *inode, struct file *filp);
extern void tty_init_termios(struct tty_struct *tty);
extern int tty_standard_install(struct tty_driver *driver,
--
2.10.1