linux-stable/kernel/printk
Sergey Senozhatsky 64ca752dcb printk: use console_trylock() in console_cpu_notify()
There is no need to always call blocking console_lock() in
console_cpu_notify(), it's quite possible that console_sem can
be locked by other CPU on the system, either already printing
or soon to begin printing the messages. console_lock() in this
case can simply block CPU hotplug for unknown period of time
(console_unlock() is time unbound). Not that hotplug is very
fast, but still, with other CPUs being online and doing
printk() console_cpu_notify() can stuck.

Use console_trylock() instead and opt-out if console_sem is
already acquired from another CPU, since that CPU will do
the printing for us.

Link: http://lkml.kernel.org/r/20170121104729.8585-1-sergey.senozhatsky@gmail.com
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
2017-03-24 16:09:46 +01:00
..
braille.c printk: fix parsing of "brl=" option 2016-08-26 17:39:35 -07:00
braille.h printk: move braille console support into separate braille.[ch] files 2013-07-31 14:41:03 -07:00
console_cmdline.h console: Fix console name size mismatch 2015-03-07 03:39:55 +01:00
internal.h printk: report lost messages in printk safe/nmi contexts 2017-02-08 13:50:05 +01:00
Makefile printk: introduce per-cpu safe_print seq buffer 2017-02-08 11:07:11 +01:00
printk.c printk: use console_trylock() in console_cpu_notify() 2017-03-24 16:09:46 +01:00
printk_safe.c printk: report lost messages in printk safe/nmi contexts 2017-02-08 13:50:05 +01:00