diff options
| author | Frank Rowand <frank.rowand@am.sony.com> | 2012-05-16 18:09:36 -0700 |
|---|---|---|
| committer | Steven Rostedt <rostedt@rostedt.homelinux.com> | 2012-10-11 14:21:42 -0400 |
| commit | 848000452ab2a740c410c4922805a9dad94a1653 (patch) | |
| tree | c4fc4359daa93b3cce7177df36d0c9d9aefc257c | |
| parent | 45fa31684a25c2ad4d65523c3c25f4c2f2fa452b (diff) | |
fix printk flush of messages
Updates console-make-rt-friendly.patch
#ifdef CONFIG_PREEMPT_RT_FULL, printk() output is never flushed by
printk() because:
# some liberties taken in this pseudo-code to make it easier to follow
printk()
vprintk()
raw_spin_lock(&logbuf_lock)
# increment preempt_count():
preempt_disable()
result = console_trylock_for_printk()
retval = 0
# lock will always be false, because preempt_count() will be >= 1
lock = ... && !preempt_count()
if (lock)
retval = 1
return retval
# result will always be false since lock will always be false
if (result)
console_unlock()
# this is where the printk() output would be flushed
On system boot some printk() output is flushed because register_console()
and tty_open() call console_unlock().
This change also fixes the problem that was previously fixed by
preempt-rt-allow-immediate-magic-sysrq-output-for-preempt_rt_full.patch
Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Cc: Frank <Frank_Rowand@sonyusa.com>
Link: http://lkml.kernel.org/r/4FB44FD0.4090800@am.sony.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| -rw-r--r-- | kernel/printk.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 9eabbbbae463..66e83e576df2 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -836,7 +836,7 @@ static int console_trylock_for_printk(unsigned int cpu, unsigned long flags) int retval = 0, wake = 0; #ifdef CONFIG_PREEMPT_RT_FULL int lock = (!early_boot_irqs_disabled && !irqs_disabled_flags(flags) && - !preempt_count()) || sysrq_in_progress; + (preempt_count() <= 1)) || sysrq_in_progress; #else int lock = 1; #endif |