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Commit 391d6276 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'core-printk-for-linus' of... 

Merge branch 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  lockdep: Fix trace_[soft,hard]irqs_[on,off]() recursion
  printk: Fix console_sem vs logbuf_lock unlock race
  printk: Release console_sem after logbuf_lock
parents 75b56ec2 dd4e5d3a

kernel/lockdep.c

+20 −10
Original line number Diff line number Diff line
@@ -2481,15 +2481,10 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark) 
/*

 * Hardirqs will be enabled:

 */

void trace_hardirqs_on_caller(unsigned long ip)

static void __trace_hardirqs_on_caller(unsigned long ip)

{

	struct task_struct *curr = current;



	time_hardirqs_on(CALLER_ADDR0, ip);



	if (unlikely(!debug_locks || current->lockdep_recursion))

		return;



	if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))

		return;
@@ -2505,8 +2500,6 @@ void trace_hardirqs_on_caller(unsigned long ip) 
	/* we'll do an OFF -> ON transition: */

	curr->hardirqs_enabled = 1;



	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))

		return;

	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))

		return;

	/*
@@ -2528,6 +2521,21 @@ void trace_hardirqs_on_caller(unsigned long ip) 
	curr->hardirq_enable_event = ++curr->irq_events;

	debug_atomic_inc(hardirqs_on_events);

}



void trace_hardirqs_on_caller(unsigned long ip)

{

	time_hardirqs_on(CALLER_ADDR0, ip);



	if (unlikely(!debug_locks || current->lockdep_recursion))

		return;



	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))

		return;



	current->lockdep_recursion = 1;

	__trace_hardirqs_on_caller(ip);

	current->lockdep_recursion = 0;

}

EXPORT_SYMBOL(trace_hardirqs_on_caller);



void trace_hardirqs_on(void)
@@ -2577,7 +2585,7 @@ void trace_softirqs_on(unsigned long ip) 
{

	struct task_struct *curr = current;



	if (unlikely(!debug_locks))

	if (unlikely(!debug_locks || current->lockdep_recursion))

		return;



	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
@@ -2588,6 +2596,7 @@ void trace_softirqs_on(unsigned long ip) 
		return;

	}



	current->lockdep_recursion = 1;

	/*

	 * We'll do an OFF -> ON transition:

	 */
@@ -2602,6 +2611,7 @@ void trace_softirqs_on(unsigned long ip) 
	 */

	if (curr->hardirqs_enabled)

		mark_held_locks(curr, SOFTIRQ);

	current->lockdep_recursion = 0;

}



/*
@@ -2611,7 +2621,7 @@ void trace_softirqs_off(unsigned long ip) 
{

	struct task_struct *curr = current;



	if (unlikely(!debug_locks))

	if (unlikely(!debug_locks || current->lockdep_recursion))

		return;



	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))

kernel/printk.c

+21 −3
Original line number Diff line number Diff line
@@ -782,7 +782,7 @@ static inline int can_use_console(unsigned int cpu) 
static int console_trylock_for_printk(unsigned int cpu)

	__releases(&logbuf_lock)

{

	int retval = 0;

	int retval = 0, wake = 0;



	if (console_trylock()) {

		retval = 1;
@@ -795,12 +795,14 @@ static int console_trylock_for_printk(unsigned int cpu) 
		 */

		if (!can_use_console(cpu)) {

			console_locked = 0;

			up(&console_sem);

			wake = 1;

			retval = 0;

		}

	}

	printk_cpu = UINT_MAX;

	spin_unlock(&logbuf_lock);

	if (wake)

		up(&console_sem);

	return retval;

}

static const char recursion_bug_msg [] =
@@ -1242,7 +1244,7 @@ void console_unlock(void) 
{

	unsigned long flags;

	unsigned _con_start, _log_end;

	unsigned wake_klogd = 0;

	unsigned wake_klogd = 0, retry = 0;



	if (console_suspended) {

		up(&console_sem);
@@ -1251,6 +1253,7 @@ void console_unlock(void) 


	console_may_schedule = 0;



again:

	for ( ; ; ) {

		spin_lock_irqsave(&logbuf_lock, flags);

		wake_klogd |= log_start - log_end;
@@ -1271,8 +1274,23 @@ void console_unlock(void) 
	if (unlikely(exclusive_console))

		exclusive_console = NULL;



	spin_unlock(&logbuf_lock);



	up(&console_sem);



	/*

	 * Someone could have filled up the buffer again, so re-check if there's

	 * something to flush. In case we cannot trylock the console_sem again,

	 * there's a new owner and the console_unlock() from them will do the

	 * flush, no worries.

	 */

	spin_lock(&logbuf_lock);

	if (con_start != log_end)

		retry = 1;

	spin_unlock_irqrestore(&logbuf_lock, flags);

	if (retry && console_trylock())

		goto again;



	if (wake_klogd)

		wake_up_klogd();

}