Char: mxser_new, fix recursive locking

Signed-off-by: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Acked-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/char/mxser_new.c b/drivers/char/mxser_new.c
index 9af07e4999d5..59e0aac19c2f 100644
--- a/drivers/char/mxser_new.c
+++ b/drivers/char/mxser_new.c
@@ -2230,7 +2230,14 @@ end_intr:
         port->mon_data.rxcnt += cnt;
         port->mon_data.up_rxcnt += cnt;
 
+        /*
+         * We are called from an interrupt context with &port->slock
+         * being held. Drop it temporarily in order to prevent
+         * recursive locking.
+         */
+        spin_unlock(&port->slock);
         tty_flip_buffer_push(tty);
+        spin_lock(&port->slock);
 }
 
 static void mxser_transmit_chars(struct mxser_port *port)