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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
This commit is contained in:
Linus Torvalds 2011-07-22 16:43:49 -07:00
parent 75b56ec294 dd4e5d3ac4
commit 391d6276db
2 changed files with 41 additions and 13 deletions
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30
kernel/lockdep.c
View File

@ -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()))

24
kernel/printk.c
View File

@ -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();
}