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author | Frank Rowand <frank.rowand@am.sony.com> | 2012-05-16 18:09:36 -0700 |
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committer | Steven Rostedt <rostedt@rostedt.homelinux.com> | 2013-02-14 12:34:44 -0500 |
commit | ed9ac9d5daf6514ac7c13ff1cdc67a56c91c83a5 (patch) | |
tree | d338890c10c84f5e53301fb57735a8c17987b703 /drivers/tty/serial/cpm_uart/cpm_uart_core.c | |
parent | 2935d8ef7d78c66bf656c6fcd72b5d8fa8e2ca16 (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>
Diffstat (limited to 'drivers/tty/serial/cpm_uart/cpm_uart_core.c')
0 files changed, 0 insertions, 0 deletions