Merge tag 'tty-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial driver updates from Greg KH:
 "Here are the big set of tty and serial driver updates for 5.6-rc1

  Included in here are:
   - dummy_con cleanups (touches lots of arch code)
   - sysrq logic cleanups (touches lots of serial drivers)
   - samsung driver fixes (wasn't really being built)
   - conmakeshash move to tty subdir out of scripts
   - lots of small tty/serial driver updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (140 commits)
  tty: n_hdlc: Use flexible-array member and struct_size() helper
  tty: baudrate: SPARC supports few more baud rates
  tty: baudrate: Synchronise baud_table[] and baud_bits[]
  tty: serial: meson_uart: Add support for kernel debugger
  serial: imx: fix a race condition in receive path
  serial: 8250_bcm2835aux: Document struct bcm2835aux_data
  serial: 8250_bcm2835aux: Use generic remapping code
  serial: 8250_bcm2835aux: Allocate uart_8250_port on stack
  serial: 8250_bcm2835aux: Suppress register_port error on -EPROBE_DEFER
  serial: 8250_bcm2835aux: Suppress clk_get error on -EPROBE_DEFER
  serial: 8250_bcm2835aux: Fix line mismatch on driver unbind
  serial_core: Remove unused member in uart_port
  vt: Correct comment documenting do_take_over_console()
  vt: Delete comment referencing non-existent unbind_con_driver()
  arch/xtensa/setup: Drop dummy_con initialization
  arch/x86/setup: Drop dummy_con initialization
  arch/unicore32/setup: Drop dummy_con initialization
  arch/sparc/setup: Drop dummy_con initialization
  arch/sh/setup: Drop dummy_con initialization
  arch/s390/setup: Drop dummy_con initialization
  ...

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
index 4f24e46ebe7c..56db949a7b70 100644
--- a/drivers/char/ttyprintk.c
+++ b/drivers/char/ttyprintk.c
@@ -15,10 +15,11 @@
 #include <linux/serial.h>
 #include <linux/tty.h>
 #include <linux/module.h>
+#include <linux/spinlock.h>
 
 struct ttyprintk_port {
 	struct tty_port port;
-	struct mutex port_write_mutex;
+	spinlock_t spinlock;
 };
 
 static struct ttyprintk_port tpk_port;
@@ -99,11 +100,12 @@ static int tpk_open(struct tty_struct *tty, struct file *filp)
 static void tpk_close(struct tty_struct *tty, struct file *filp)
 {
 	struct ttyprintk_port *tpkp = tty->driver_data;
+	unsigned long flags;
 
-	mutex_lock(&tpkp->port_write_mutex);
+	spin_lock_irqsave(&tpkp->spinlock, flags);
 	/* flush tpk_printk buffer */
 	tpk_printk(NULL, 0);
-	mutex_unlock(&tpkp->port_write_mutex);
+	spin_unlock_irqrestore(&tpkp->spinlock, flags);
 
 	tty_port_close(&tpkp->port, tty, filp);
 }
@@ -115,13 +117,14 @@ static int tpk_write(struct tty_struct *tty,
 		const unsigned char *buf, int count)
 {
 	struct ttyprintk_port *tpkp = tty->driver_data;
+	unsigned long flags;
 	int ret;
 
 
 	/* exclusive use of tpk_printk within this tty */
-	mutex_lock(&tpkp->port_write_mutex);
+	spin_lock_irqsave(&tpkp->spinlock, flags);
 	ret = tpk_printk(buf, count);
-	mutex_unlock(&tpkp->port_write_mutex);
+	spin_unlock_irqrestore(&tpkp->spinlock, flags);
 
 	return ret;
 }
@@ -171,7 +174,7 @@ static int __init ttyprintk_init(void)
 {
 	int ret = -ENOMEM;
 
-	mutex_init(&tpk_port.port_write_mutex);
+	spin_lock_init(&tpk_port.spinlock);
 
 	ttyprintk_driver = tty_alloc_driver(1,
 			TTY_DRIVER_RESET_TERMIOS |