tty: n_tty: extract n_tty_continue_cookie() from n_tty_read()

n_tty_read() is a very long function doing too much of different stuff.
Extract the "cookie" (continuation read) handling to a separate
function: n_tty_continue_cookie().

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-10-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 43ba740792d924b9ab609aab75efee5b5cbe088e..88aa5f9cbe5e007b80b4cd4cc2c64a34d08a55c5 100644 (file)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2111,6 +2111,39 @@ static int job_control(struct tty_struct *tty, struct file *file)
        return __tty_check_change(tty, SIGTTIN);
 }
 
+/*
+ * We still hold the atomic_read_lock and the termios_rwsem, and can just
+ * continue to copy data.
+ */
+static ssize_t n_tty_continue_cookie(struct tty_struct *tty, u8 *kbuf,
+                                  size_t nr, void **cookie)
+{
+       struct n_tty_data *ldata = tty->disc_data;
+       u8 *kb = kbuf;
+
+       if (ldata->icanon && !L_EXTPROC(tty)) {
+               /*
+                * If we have filled the user buffer, see if we should skip an
+                * EOF character before releasing the lock and returning done.
+                */
+               if (!nr)
+                       canon_skip_eof(ldata);
+               else if (canon_copy_from_read_buf(tty, &kb, &nr))
+                       return kb - kbuf;
+       } else {
+               if (copy_from_read_buf(tty, &kb, &nr))
+                       return kb - kbuf;
+       }
+
+       /* No more data - release locks and stop retries */
+       n_tty_kick_worker(tty);
+       n_tty_check_unthrottle(tty);
+       up_read(&tty->termios_rwsem);
+       mutex_unlock(&ldata->atomic_read_lock);
+       *cookie = NULL;
+
+       return kb - kbuf;
+}
 
 /**
  * n_tty_read          -       read function for tty
@@ -2144,36 +2177,9 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, u8 *kbuf,
        bool packet;
        size_t old_tail;
 
-       /*
-        * Is this a continuation of a read started earler?
-        *
-        * If so, we still hold the atomic_read_lock and the
-        * termios_rwsem, and can just continue to copy data.
-        */
-       if (*cookie) {
-               if (ldata->icanon && !L_EXTPROC(tty)) {
-                       /*
-                        * If we have filled the user buffer, see
-                        * if we should skip an EOF character before
-                        * releasing the lock and returning done.
-                        */
-                       if (!nr)
-                               canon_skip_eof(ldata);
-                       else if (canon_copy_from_read_buf(tty, &kb, &nr))
-                               return kb - kbuf;
-               } else {
-                       if (copy_from_read_buf(tty, &kb, &nr))
-                               return kb - kbuf;
-               }
-
-               /* No more data - release locks and stop retries */
-               n_tty_kick_worker(tty);
-               n_tty_check_unthrottle(tty);
-               up_read(&tty->termios_rwsem);
-               mutex_unlock(&ldata->atomic_read_lock);
-               *cookie = NULL;
-               return kb - kbuf;
-       }
+       /* Is this a continuation of a read started earlier? */
+       if (*cookie)
+               return n_tty_continue_cookie(tty, kbuf, nr, cookie);
 
        retval = job_control(tty, file);
        if (retval < 0)