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|
Subject: printk-rt-aware.patch
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 19 Sep 2012 14:50:37 +0200
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/printk.c | 33 +++++++++++++++++++++++++++++----
1 file changed, 29 insertions(+), 4 deletions(-)
Index: linux-stable/kernel/printk.c
===================================================================
--- linux-stable.orig/kernel/printk.c
+++ linux-stable/kernel/printk.c
@@ -1312,6 +1312,7 @@ static void call_console_drivers(int lev
if (!console_drivers)
return;
+ migrate_disable();
for_each_console(con) {
if (exclusive_console && con != exclusive_console)
continue;
@@ -1324,6 +1325,7 @@ static void call_console_drivers(int lev
continue;
con->write(con, text, len);
}
+ migrate_enable();
}
/*
@@ -1383,12 +1385,18 @@ static inline int can_use_console(unsign
* interrupts disabled. It should return with 'lockbuf_lock'
* released but interrupts still disabled.
*/
-static int console_trylock_for_printk(unsigned int cpu)
+static int console_trylock_for_printk(unsigned int cpu, unsigned long flags)
__releases(&logbuf_lock)
{
int retval = 0, wake = 0;
+#ifdef CONFIG_PREEMPT_RT_FULL
+ int lock = !early_boot_irqs_disabled && !irqs_disabled_flags(flags) &&
+ (preempt_count() <= 1);
+#else
+ int lock = 1;
+#endif
- if (console_trylock()) {
+ if (lock && console_trylock()) {
retval = 1;
/*
@@ -1667,8 +1675,15 @@ asmlinkage int vprintk_emit(int facility
* The console_trylock_for_printk() function will release 'logbuf_lock'
* regardless of whether it actually gets the console semaphore or not.
*/
- if (console_trylock_for_printk(this_cpu))
+ if (console_trylock_for_printk(this_cpu, flags)) {
+#ifndef CONFIG_PREEMPT_RT_FULL
+ console_unlock();
+#else
+ raw_local_irq_restore(flags);
console_unlock();
+ raw_local_irq_save(flags);
+#endif
+ }
lockdep_on();
out_restore_irqs:
@@ -2057,11 +2072,16 @@ static void console_cont_flush(char *tex
goto out;
len = cont_print_text(text, size);
+#ifndef CONFIG_PREEMPT_RT_FULL
raw_spin_unlock(&logbuf_lock);
stop_critical_timings();
call_console_drivers(cont.level, text, len);
start_critical_timings();
local_irq_restore(flags);
+#else
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+ call_console_drivers(cont.level, text, len);
+#endif
return;
out:
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
@@ -2144,12 +2164,17 @@ skip:
console_idx = log_next(console_idx);
console_seq++;
console_prev = msg->flags;
- raw_spin_unlock(&logbuf_lock);
+#ifndef CONFIG_PREEMPT_RT_FULL
+ raw_spin_unlock(&logbuf_lock);
stop_critical_timings(); /* don't trace print latency */
call_console_drivers(level, text, len);
start_critical_timings();
local_irq_restore(flags);
+#else
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+ call_console_drivers(level, text, len);
+#endif
}
console_locked = 0;
|
