summaryrefslogtreecommitdiff
path: root/drivers
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2020-12-16 10:45:11 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-16 10:45:11 -0800
commitd3eb52113d162cc88975fbd03c9e6f9cf2f8a771 (patch)
tree7ef2b73e6174d355d625c2a05377b14c0939cca7 /drivers
parent5e60366d56c630e32befce7ef05c569e04391ca3 (diff)
parent5ed37174e6c7e1ed4abfd0d8e932a3044441fb5f (diff)
Merge tag 'printk-for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek: - Finally allow parallel writes and reads into/from the lockless ringbuffer. But it is not a complete solution. Readers are still serialized against each other. And nested writes are still prevented by printk_safe per-CPU buffers. - Use ttynull as the ultimate fallback for /dev/console. - Officially allow disabling console output by using console="" or console=null - A few code cleanups * tag 'printk-for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: remove logbuf_lock writer-protection of ringbuffer printk: inline log_output(),log_store() in vprintk_store() printk: remove obsolete dead assignment printk/console: Allow to disable console output by using console="" or console=null init/console: Use ttynull as a fallback when there is no console printk: ringbuffer: Reference text_data_ring directly in callees.
Diffstat (limited to 'drivers')
-rw-r--r--drivers/tty/Kconfig14
-rw-r--r--drivers/tty/Makefile3
-rw-r--r--drivers/tty/ttynull.c18
3 files changed, 19 insertions, 16 deletions
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index e15cd6b5bb99..47a6e42f0d04 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -401,20 +401,6 @@ config MIPS_EJTAG_FDC_KGDB_CHAN
help
FDC channel number to use for KGDB.
-config NULL_TTY
- tristate "NULL TTY driver"
- help
- Say Y here if you want a NULL TTY which simply discards messages.
-
- This is useful to allow userspace applications which expect a console
- device to work without modifications even when no console is
- available or desired.
-
- In order to use this driver, you should redirect the console to this
- TTY, or boot the kernel with console=ttynull.
-
- If unsure, say N.
-
config TRACE_ROUTER
tristate "Trace data router for MIPI P1149.7 cJTAG standard"
depends on TRACE_SINK
diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
index b3ccae932660..3c1c5a9240a7 100644
--- a/drivers/tty/Makefile
+++ b/drivers/tty/Makefile
@@ -2,7 +2,7 @@
obj-$(CONFIG_TTY) += tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o \
tty_buffer.o tty_port.o tty_mutex.o \
tty_ldsem.o tty_baudrate.o tty_jobctrl.o \
- n_null.o
+ n_null.o ttynull.o
obj-$(CONFIG_LEGACY_PTYS) += pty.o
obj-$(CONFIG_UNIX98_PTYS) += pty.o
obj-$(CONFIG_AUDIT) += tty_audit.o
@@ -25,7 +25,6 @@ obj-$(CONFIG_ISI) += isicom.o
obj-$(CONFIG_MOXA_INTELLIO) += moxa.o
obj-$(CONFIG_MOXA_SMARTIO) += mxser.o
obj-$(CONFIG_NOZOMI) += nozomi.o
-obj-$(CONFIG_NULL_TTY) += ttynull.o
obj-$(CONFIG_ROCKETPORT) += rocket.o
obj-$(CONFIG_SYNCLINK_GT) += synclink_gt.o
obj-$(CONFIG_PPC_EPAPR_HV_BYTECHAN) += ehv_bytechan.o
diff --git a/drivers/tty/ttynull.c b/drivers/tty/ttynull.c
index 17f05b7eb6d3..eced70ec54e1 100644
--- a/drivers/tty/ttynull.c
+++ b/drivers/tty/ttynull.c
@@ -2,6 +2,13 @@
/*
* Copyright (C) 2019 Axis Communications AB
*
+ * The console is useful for userspace applications which expect a console
+ * device to work without modifications even when no console is available
+ * or desired.
+ *
+ * In order to use this driver, you should redirect the console to this
+ * TTY, or boot the kernel with console=ttynull.
+ *
* Based on ttyprintk.c:
* Copyright (C) 2010 Samo Pogacnik
*/
@@ -59,6 +66,17 @@ static struct console ttynull_console = {
.device = ttynull_device,
};
+void __init register_ttynull_console(void)
+{
+ if (!ttynull_driver)
+ return;
+
+ if (add_preferred_console(ttynull_console.name, 0, NULL))
+ return;
+
+ register_console(&ttynull_console);
+}
+
static int __init ttynull_init(void)
{
struct tty_driver *driver;