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authorStephen Chivers <schivers@csc.com>2014-05-14 08:04:39 +1000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-05-28 13:07:27 -0700
commit7fa21dd8bd191564a195291161d6b43db5d9c350 (patch)
treefa2e01328a932ad906f3bb6f704973dda716c9ea /kernel/printk/printk.c
parentd4089a332883ad969700aac5dd4dd5f1c4fee825 (diff)
downloadlwn-7fa21dd8bd191564a195291161d6b43db5d9c350.tar.gz
lwn-7fa21dd8bd191564a195291161d6b43db5d9c350.zip
printk/of_serial: fix serial console cessation part way through boot.
Commit 5f5c9ae56c38942623f69c3e6dc6ec78e4da2076 "serial_core: Unregister console in uart_remove_one_port()" fixed a crash where a serial port was removed but not deregistered as a console. There is a side effect of that commit for platforms having serial consoles and of_serial configured (CONFIG_SERIAL_OF_PLATFORM). The serial console is disabled midway through the boot process. This cessation of the serial console affects PowerPC computers such as the MVME5100 and SAM440EP. The sequence is: bootconsole [udbg0] enabled .... serial8250/16550 driver initialises and registers its UARTS, one of these is the serial console. console [ttyS0] enabled .... of_serial probes "platform" devices, registering them as it goes. One of these is the serial console. console [ttyS0] disabled. The disabling of the serial console is due to: a. unregister_console in printk not clearing the CONS_ENABLED bit in the console flags, even though it has announced that the console is disabled; and b. of_platform_serial_probe in of_serial not setting the port type before it registers with serial8250_register_8250_port. This patch ensures that the serial console is re-enabled when of_serial registers a serial port that corresponds to the designated console. Signed-off-by: Stephen Chivers <schivers@csc.com> Tested-by: Stephen Chivers <schivers@csc.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [unregister_console] Cc: stable <stable@vger.kernel.org> # 3.15 === The above failure was identified in Linux-3.15-rc2. Tested using MVME5100 and SAM440EP PowerPC computers with kernels built from Linux-3.15-rc5 and tty-next. The continued operation of the serial console is vital for computers such as the MVME5100 as that Single Board Computer does not have any grapical/display hardware. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/printk/printk.c')
-rw-r--r--kernel/printk/printk.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index a45b50962295..81c71617ea28 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2413,6 +2413,7 @@ int unregister_console(struct console *console)
if (console_drivers != NULL && console->flags & CON_CONSDEV)
console_drivers->flags |= CON_CONSDEV;
+ console->flags &= ~CON_ENABLED;
console_unlock();
console_sysfs_notify();
return res;